As has been the case since 2013, all teams will play their four division opponents 19 times each for a total of 76 games. They will play six or seven games against each of the other ten same-league opponents for a total of 66 games, and 20 interleague games. The primary interleague match-ups are AL East vs NL East, AL Central vs NL Central, and AL West vs NL West. Since "natural rivalry" matchups are part of the three-year divisional rotation, the schedule format for interleague games will be different from previous years. The 20 interleague games each team will play will consist of two three-game series (one home, one away) against its natural rival (total of six games), two two-game series (one home, one away) against each team for two other opponents (total of eight games), and a single three-game series against each team for the last two (one home, one away; total of six games).
Under the new collective bargaining agreement reached in December 2016, the regular season was extended to 187 days in order to add four additional off-days for all teams. All teams were scheduled to play Opening Day, March 29 – the earliest domestic start of a regular season in league history until the 2019 season. The Sunday night game before the All-Star Game was replaced by a single, nationally-televised game on the Thursday after the All-Star Game (which for 2018, was played between the St. Louis Cardinals and Chicago Cubs), before all other teams returned from break the next day.
Beginning in the 2018 season, MLB implemented new pace of play rules, which include limiting the number of mound visits for each team to six per nine innings. Teams will receive an additional visit for every extra inning played.
John Coppolella resigned from the Braves on October 2, 2017, because of a Major League Baseball investigation regarding signing bonuses of international prospects. On November 12, 2017, Alex Anthopoulos was hired as the new general manager of the team. On November 21, 2017, Coppolella was banned for life from baseball as a result of the investigation. The Braves were penalized with a loss of 13 prospects and a 2018 Rule 4 draft (third round) pick, and the league levied other penalties against the team for the next two international signing periods.
On June 26, 2018, Alderson took a permanent leave of absence due to recurrence of cancer. He was hired as general manager in 2010 and saw the team win the National League Pennant in 2015. On October 28, 2018, after having three interims finish the rest of the season, the Mets agreed to have former agent Brodie Van Wagenen be their 13th general manager in franchise history.
The Giants fired Bobby Evans after almost four seasons as General Manager. The Giants made the playoffs in 2016, but are 166–224 (.426) since taking a major league-best 57–33 (.633) record into the All-Star break that year.
The Tigers announced on September 22, 2017, that Ausmus' contract would not be renewed. Ausmus compiled a 314–332 (.486) record in four years as manager with one playoff appearance. The Tigers hired former Minnesota Twins manager Ron Gardenhire on October 19, 2017. As the Twins' manager from 2002 to 2014 he compiled a record of 1068–1039 (.507), and 6–21 (.222) in six post-season appearances. He also won AL Manager of the Year in 2010.
It was announced on October 1, 2017, that Mackanin would be removed as manager; however, he managed the final three games of the 2017 season. Mackanin had a record of 174–238 (.422) in his two and a half seasons as manager with no playoff appearances. It also was announced that he would remain with the organization as a special assistant to the general manager. On October 29, 2017, the Phillies announced the hire of former Dodgers' Director of Development Gabe Kapler. He had no previous major league managerial or coaching experience.
Collins announced on October 1, 2017, that he would retire after the last game of the season and move to the Mets' front office. Collins finished with a 551–583 (.486) record in seven years with club, with two playoff appearances in 2015 and 2016, in which they lost to the Kansas City Royals in the World Series and lost the Wild Card to the San Francisco Giants in the following season. The Mets named Cleveland Indians pitching coach Mickey Callaway as their new manager on October 22, 2017. Callaway had no previous managerial experience.
Farrell was fired on October 11, 2017. Farrell during his five years as manager compiled a 432–378 (.533) record and earned three division titles in 2013, 2016 and 2017. He led the Red Sox to the 2013 World Series title.Houston Astros bench coach Alex Cora was named manager on October 22, 2017, and formally assumed the role after the Astros' win in the 2017 World Series. He had no previous managerial experience.
The Nationals announced on October 20, 2017, that Baker would not be returning for the 2018 season. Baker led the Nationals to the postseason in each of his two seasons with the club but couldn't get past the NLDS. The Nationals were 192–132 (.593) under Baker. The Nationals hired Dave Martinez to be their new manager on October 29, 2017. Martinez was previously the bench coach for the Chicago Cubs and had no managerial experience.
The Yankees announced on October 26, 2017, that Girardi would not return for the 2018 season. Girardi led the Yankees to three division titles and one World Series championship during his ten years of managing the club. The Yankees were 910–710 (.562) under Girardi. On December 1, 2017, radio announcer Aaron Boone was hired as the team's new manager. He had no previous coaching or managerial experience.
Price was fired on April 19 after starting the season with a 3–15 (.167) record. In four seasons, Price finished with a 279–387 (.419) record with no playoff appearances. Bench coach Jim Riggleman was selected as the interim manager. His previous managerial experience included stints with the Padres, Cubs, Mariners, and Nationals. He had been a manager in the Reds' minor league system since 2012. On October 21, 2018, the Reds named David Bell as their new manager, signing him to a three year contract with a club option for 2022.
Matheny was fired on July 14 after starting the season with a 47–46 (.505) record. In seven seasons, Matheny finished with a 591–473 (.555) record with four playoff appearances, winning the National League pennant in 2013. Hitting coach John Mabry and assistant hitting coach Bill Mueller were also dismissed, and bench coach Mike Shildt was named interim manager. Shildt had no major league managing experience but had managed in the Cardinals minor league system. On August 28, Shildt's "interim" title was dropped as he was named the new Cardinals manager.
Banister was fired on September 21 after four seasons with a record of 325–313 (.509) record. Banister finished in first place in his first two seasons as manager and amassed a 2–6 (.250) in the playoffs. Bench coach Don Wakamatsu was selected as the interim manager. On November 2, it was announced that Los Angeles Dodgers third-base coach Chris Woodward would be named the Rangers manager.
With a second-inning double on April 5 against the Oakland Athletics, Beltré became the all-time leader in hits by a player from Latin America. Beltré, from the Dominican Republic, passed Rod Carew of Panama with the 3,054th hit in his career.
On May 25 Torres became the youngest player in American League history with home runs in four consecutive games. He homered against the Texas Rangers in back-to-back games as well as the Los Angeles Angels.
Became the all-time leader in Major League history for most home runs hit by a player from Asia by hitting his 176th career home run in the 10th inning against the Kansas City Royals on May 26. He passed Hideki Matsui for the record.
With his 30th home run of the season on July 31 against the Tampa Bay Rays, Trout became the second player in Major League history (the other being Willie Mays) to hit 30 home runs and steal 20 bases in three seasons before their age-26 campaigns.
Became the first player since Cap Anson in 1884 to give up two home runs as a pitcher in one game (on July 31) and hit two home runs the following game (on August 1). Both games were against the Washington Nationals.
With his 20th home run on the season by Acuna on August 22 against the Pittsburgh Pirates, Acuna and Albies became the first teammates in Major League history to hit 20+ home runs in the same season before either player turned 22 years old.
With a 6-for-6 day and hitting for the cycle on August 29 against the Cincinnati Reds, Yelich became the fourth player in Major League history to record six hits while also hitting for the cycle. He is the first to accomplish the feat since Ian Kinsler in 2009.
With his cycle on September 17, Yelich became the first player in Major League history to have multiple cycles against the same team in the same season.
Became the first player in Major League history (in the live ball era) to record extra-base hits in each of his first three plate appearances. Tellez recorded pinch-hit double during his debut against the Tampa Bay Rays on September 5. On September 6, Tellez doubled in the second and fourth innings against the Cleveland Indians. Tellez flied out in his next at bat.
With his first-inning double on September 11 against the Arizona Diamondbacks, Story became the first shortstop in National League history to amass 30+ home runs, 40+ doubles and drive in more than 100 runs in a season.
Threw his first career no-hitter by defeating the Boston Red Sox 3–0 on April 21, at the Oakland Coliseum. Manaea struck out ten batters, walked two and threw one wild pitch, throwing 75 of his 108 pitches for strikes. The game included two controversial out calls: in the fifth inning, a batter reached base on an error that Manaea reportedly assumed was ruled a hit; in the sixth inning, Andrew Benintendi was initially ruled safe on an infield single, but after some discussion by the umpiring crew, he was called out for having left the baseline on the play. Benintendi later called this a "missed call" and insinuated that the umpires were biased in favor of Manaea.
Threw the first combined no-hitter in franchise history by defeating the San Diego Padres 4–0 on May 4, during a series played at the Estadio de Béisbol in Monterrey, Mexico. Buehler struck out eight and walked three over six innings, throwing 59 of his 93 pitches for strikes. Cingrani struck out one and walked two over one inning, throwing 13 of 24 pitches for strikes. García struck out two and walked none over one inning, throwing 11 of 14 pitches for strikes. Liberatore also did not walk a batter, striking out 2 and throwing 10 of 15 pitches for strikes. This was the 12th combined no-hitter in Major League history and the 23rd no-hitter in franchise history.
Threw his first career no-hitter, and the sixth in franchise history, by defeating the Toronto Blue Jays 5–0 on May 8, at Rogers Centre. Paxton struck out seven and walked three, throwing 64 of his 99 pitches for strikes. Paxton became the second Canadian-born player to throw a no-hitter, joining Dick Fowler of the 1945 Philadelphia Athletics. As the game was played in Toronto, this made Canada the third country in which an MLB no-hitter was thrown in 2018, the other two being the USA and Mexico.
Became the second pitcher in the live-ball era (since 1920) to pitch a shutout, strike out at least 10 batters and steal a base in the same game by accomplishing this feat on April 9 against the Atlanta Braves. He joins Nolan Ryan who did this against the Pittsburgh Pirates on May 16, 1984.
Became the first pitcher in Major League history to finish with no more than 61⁄3 innings and strike out 15 batters in a 5–4 win against the Philadelphia Phillies on May 6. He did not factor into the decision. 
Recorded his 150th career win with a victory against the Baltimore Orioles on May 30. He became the 259th player to reach this mark.
With his first-inning strikeout of Matt Carpenter of the St. Louis Cardinals on September 3, Scherzer recorded his fifth consecutive season of at least 250 strikeouts. He becomes the second pitcher in Major League history to accomplish this feat. He joins Randy Johnson who accomplished this in six consecutive seasons from 1997 to 2002.
With his seventh-inning strikeout of Austin Dean of the Miami Marlins on September 25, Scherzer reached his 300th strikeout of the season. He becomes the 17th pitcher since 1900 to record 300 strikeouts in a season.
On April 10, at the age of 23 years and 62 days, Osuna became the youngest pitcher in Major League history to record his 100th career save. Osuna was over a year younger than the previous record holder Francisco Rodríguez, who had accomplished the feat at the age of 24 years and 246 days.
With his victory on June 18 against the Kansas City Royals, Colón became the winningest pitcher in Major League history from the Dominican Republic. His 244th career win passed Hall of Famer Juan Marichal.
With his victory on August 7 against the Seattle Mariners, Colón became the winningest Latin American-born pitcher in Major League history, passing Nicaragua's Dennis Martínez.
Recorded his 50th save of the season by closing out a win against the Arizona Diamondbacks on August 25. With this save, he became the 16th player in Major League history, and the youngest to do so, to record 50 saves.
Against the Miami Marlins on September 11, deGrom allowed two runs in seven innings of work. This was his 26th consecutive start of allowing three or fewer runs, setting a new Major League record. The old record was set by Leslie "King" Cole in 1910.
With his quality start – at least six innings pitched and three earned runs or fewer allowed – on September 21 against the Washington Nationals, deGrom set the Major League record for most consecutive quality starts in history with his 23rd straight. This broke the record set by Bob Gibson (1968) and Chris Carpenter (2005).
For the first time in Major League history, there were more strikeouts than hits in a month. At the end of April, there were 7,335 strikeouts and 6,992 hits. This happened again two other times. In June, there were 6,776 strikeouts and 6,641 hits. In September, there were 7,074 strikeouts and 6,641 hits.
The Houston Astros broke the record for the fewest runs allowed since 1920 (live ball era) in a 50-game span with 126 runs. The previous record was 128 set by the Cleveland Indians in 1968.
On August 16, the Texas Rangers pulled off a 5–4 triple play in their 8–6 win over the Los Angeles Angels. It was only the third 5–4 triple play in the expansion era (since 1961), with the most recent one having occurred in 2007. In addition, it was the first triple play since 1912 in which the batter was not retired.
On September 20 against the Oakland Athletics, Arcia became the first player in Major League history to catch, pitch, and hit a home run in the same game.
For the first time in Major League history, there were more strikeouts than hits for the season. Hitters struck out 41,207 times and recorded 41,019 hits.
The Houston Astros set a Major League record for fewest runs allowed by an American League pitching staff in the Designated Hitter era with 534 runs allowed. The previous record was 551 runs allowed by the Oakland Athletics in 1974. The Astros also set a Major League record for strikeouts by a pitching staff with 1687 total strikeouts on the 2018 season. The previous record was 1614 strikeouts by the Cleveland Indians in 2017.
On October 26, 2018, the Boston Red Sox and Los Angeles Dodgers squared off in what would become the longest World Series game in history, both by innings and time. Game 3 ran 18 innings over 7 hours and 20 minutes. The Dodgers would emerge victorious 3–2, off an opposite field walk-off home run hit by Max Muncy. This would cut Boston's lead in the series to 2–1.
The Detroit Tigers modified the Olde English 'D' on the home jersey to match the 'D' on the cap. Other than a one-season hiatus of 'D' usage in 1960, this is the first major change to the Tigers' home jersey since 1934.
The Cleveland Indians have confirmed this will be the final season using the Chief Wahoo logo on its uniforms. It will be replaced at the start of the 2019 season. The team wore a Wahoo-less uniform through their September 6-9 series with the Blue Jays, as the team had been sued unsuccessfully by a group in Ontario in October 2016 to prevent the team from donning the logo during Toronto home games through the 2016 ALCS.
The Oakland Athletics added a kelly green alternate jersey to commemorate the franchise's 50th anniversary in Oakland. The uniforms are used during every Friday home game.
The Washington Nationals added a second navy blue jersey to commemorate the team's hosting of the 2018 All-Star Game. The uniform features the script "Nationals" in white with red trim and numerals in red with white trim. 
Both the Cincinnati Reds and the Pittsburgh Pirates replaced their camouflage uniforms with new white alternate jerseys featuring olive and military green logos, letters and numbers.
Anniversaries and special events
The following teams will wear commemorative patches for special occasions:
As is the custom for the reigning World Series champions, the Astros wore gold-lettered uniforms at their home opener April 2 and April 3.
Players, managers and coaches wore #42 on April 15, the 71st anniversary of Jackie Robinson's debut in the majors.
The Orioles wore special caps and green uniforms on April 22, Earth Day.
The Reds and Diamondbacks wore Spanish language "Los Rojos" and "Los D-backs" uniforms May 5, Cinco de Mayo. The Diamondbacks wore them again September 8. The Reds wore them again September 28.
The Royals wore an alternate uniform with a crown atop the R, and a cap with a crown instead of the "KC", on June 30 in Seattle.
The Blue Jays wore red uniforms on July 1, Canada Day. They wore a cap with a gold maple leaf, as well.
All US-based teams wore Stars and Stripes caps and uniforms from July 2–4, ending with Independence Day. Teams wore caps denoting what league they play for (there were nine interleague series during the time period).
The Royals wore Spanish-language "Los Reales" uniforms September 1.
The Orioles wore Braille uniforms September 18 to mark the 40th anniversary of the National Federation of the Blind's headquarters moving to Baltimore. They became the first pro sports team ever to wear such uniforms. The uniforms had the name "Orioles" in Braille, and the players' last names were in Braille.
The Phillies will wear their 1980s powder blue uniforms for select Thursday home games.
The Athletics and White Sox wore 1968 throwbacks April 17 to mark the 50th anniversary of the Athletics' first season in Oakland.
The Brewers wore Milwaukee Bears uniforms August 2. Their opponents, the Rockies, wore their regular uniforms.
The Mariners and Astros wore throwbacks on August 10; the Mariners wore their 1979 throwbacks, and the Astros wore their "Tequila Sunrise" uniforms.
The Angels wore California Angels throwbacks from 1976-1985 on August 27.
The Rays wore their 1998 inaugural throwbacks on March 31 against the Boston Red Sox, on June 9 against the Seattle Mariners, and on June 23 against the New York Yankees, along with September 8 against the Baltimore Orioles.
The Tigers wore their 1968 road uniforms September 8 at home to mark the 50th anniversary of their winning the 1968 World Series title.
This was the fifth year of the current eight-year deals with Fox Sports, ESPN and TBS. Fox aired eight weeks of baseball on Saturday Nights leading up to the 2018 Major League Baseball All-Star Game which also aired on Fox. Fox also televised Saturday afternoon games for the last four weeks of the regular season. FS1 televised games on Tuesday and on Saturdays both during the afternoon and night. ESPN televised games on its flagship telecast Sunday Night Baseball as well as Monday and Wednesday Nights. TBS televised Sunday afternoon games for the last 13 weeks of the regular season. Fox and ESPN Sunday Night Baseball telecasts were exclusive; all other national telecasts were subject to local blackout.
On September 6, Fox Sports Detroit suspended Detroit Tigers play-by-play announcer Mario Impemba and color commentator Rod Allen for the remainder of the season after an alleged physical altercation that occurred on September 4, in which Allen reportedly placed Impemba in a choke hold at Chicago's Guaranteed Rate Field after a game they called between the Tigers and the Chicago White Sox, a claim Allen's agent has denied. Backup announcers Matt Shepard and Kirk Gibson replaced them for the rest of the season. It was later announced that Impemba and Allen's contracts were not renewed for future seasons, ending their 17 years together as broadcast partners.
The Minnesota Twins returned to Entercom's WCCO/Minneapolis after twelve years on KSTP, followed by the Twins-owned FM station KQGO; WCCO has been the flagship for the Twins' network for 46 of the team's 58 years of existence. Entercom will also take over all existing play-by-play contracts from their newly acquired stations from CBS Radio after the two companies merged their radio assets on November 17, 2017.
The Chicago White Sox took on a new flagship station in Tribune Broadcasting's WGN/Chicago, after Cumulus Media asked to void their agreement to carry the team's games on WLS as part of its Chapter 11 bankruptcy filing, and Cumulus ending several high-profile talent and sports rights agreements due to their cost. The deal allows WGN to return to MLB play-by-play after a three-year hiatus after the end of their long association with the Chicago Cubs, who moved to WBBM in the 2015 season, then WSCR in 2016. WGN had previously carried White Sox broadcasts from 1927 until 1943.
The San Diego Padres obtained a new flagship station after Entercom moved the team's broadcasts from KBZT to KEGY (both FM stations), which had flipped from a contemporary hit radio format to a short-lived hot talk format at the beginning of the season. After the team and fans reacted negatively to the schedule and personalities surrounding Padres games following a controversial social media post involving a never-launched morning show (to the point of consideration by the Padres to void the broadcast contract only three games into the season), Entercom switched KEGY within two weeks to a straight sports radio format and new calls in KWFN.