For nearly 75 years after its publication, the music of ’O sole mio had generally been attributed to Eduardo di Capua alone. According to the traditional account, di Capua had composed it in April 1898 in Odessa, while touring with his father's band. It has turned out, however, that the melody was an elaboration of one of 23 which di Capua had bought from another musician, Alfredo Mazzucchi, in the preceding year.
In November 1972, shortly after her father's death, Mazzucchi's daughter lodged a declaration with Italy’s Office of Literary, Artistic and Scientific Property, which sought to have her father recognised as a co-composer of 18 of di Capua's songs, including ’O sole mio. In October 2002, Maria Alvau, a judge in Turin, upheld the declaration, ruling that Mazzucchi had indeed been a legitimate co-composer of the 18 songs, because they included melodies he had composed and then sold to di Capua in June of 1897, with a written authorisation for the latter to make free use of them. At the time of the decision, therefore, the melody of ’O sole mio had not yet—as had been widely supposed—entered into the public domain in any country that was a party to the Berne Convention during the relevant period. In most countries where copyright in a work lasts for 70 years after any of its authors' deaths, the melody will remain under copyright until 2042.
In 1915, Charles W. Harrison recorded the first English translation of "’O sole mio". In 1921, William E. Booth-Clibborn wrote lyrics for a hymn using the music, entitled "Down from His Glory."
In 1949 U.S. singer Tony Martin recorded "There's No Tomorrow" with lyrics by Al Hoffman, Leo Corday, and Leon Carr, which used the melody of "’O sole mio". About ten years later, while stationed in West Germany with the U.S. Army, Elvis Presley heard the recording and put to tape a private version of the song. Upon his discharge, he requested that new lyrics be written especially for him, a job that was undertaken by the songwriting duo of Aaron Schroeder and Wally Gold, with a demo by David Hill. The rewritten version was entitled "It's Now or Never" and was a worldwide hit for Presley. When performing it in concert in the mid-1970s, Elvis would explain the origin of "It's Now Or Never" and have singer Sherrill Nielsen perform a few lines of the original Neapolitan version before commencing with his version.
Vic Damone included the song in his album Angela mia (1958).
Bing Crosby included the song in a medley on his album 101 Gang Songs (1961).
A series of television commercials for Cornetto ice cream, broadcast regularly in Britain during the 1980s, used a jingle ("Just One Cornetto ...") set to the melody of "’O sole mio". The jingle was widely reported as having been performed by Renato Pagliari, but after Pagliari's death in 2009, his son denied this.
In a late 1970s Sesame Street sequence, Ernie sings a spoof on the song ("O solo mio, o solo you-o") loudly out the window of his and Bert's apartment to wake neighbors up so he can find out what time it is.[better source needed]
In 1961, while becoming the first person to ever orbit the earth, Russian cosmonaut Yuri Gagarin hummed "O Sole Mio".
As of 2002, the song's yearly royalties were estimated to be at least $250,000.
^Del Bosco (2006, pp. 119, 120, 124–26). Pages 119 and 120 contain a literal translation into standard Italian, and Capurro's own rendering into a non-literal poetic version in that language, respectively. Pages 124 to 126 contain three non-literal versions of lyrics in English.
^ abLiterally, "Oh baby (girl)", but commonly used, as here, by a suitor as a term of endearment when addressing his sweetheart, the term "ne’" being a contraction of "nenna", and meaning "baby girl", or "young girl" (Del Bosco 2006, p. 103). The widely circulated rendering of this as "non c'è" in Italian (i.e. "there is not" in English) is an error (Del Bosco 2006, pp. 101–2).