The song was the first released on Carmen's first solo LP after leaving the power pop group the Raspberries and was released as the first single in December 1975 to great success. It reached number 2 on the Billboard Hot 100, number 1 on Cash Box Top 100 Singles and number 3 in Canada. The single sold more than one million copies in the United States and was certified gold by the RIAA in April 1976. "All By Myself" was Carmen's first of eight U.S. Top 40 hits. In the UK, however, this was his only Top 40 hit, peaking at number 12. In a 2006 poll for UK's Five programme Britain's Favourite Break-up Songs Eric Carmen's version of this song was voted seventeenth.
Carmen thought that Rachmaninoff’s music was in the “public domain” and no copyright existed on it. Subsequent to the release of the album, Carmen was contacted by the Rachmaninoff estate and informed otherwise. An agreement was reached in which the estate would receive 12 percent of the royalties from "All By Myself" as well as "Never Gonna Fall in Love Again", which was based on the third movement from Rachmaninoff's Symphony No. 2.
Carmen has stated that he also incorporated part of another melody into this song. The melody was taken from his previous hit with the Raspberries, "Let's Pretend."
There were three music videos made. The first one was released in October 1996. It contains fragments from Dion's photo session for the Falling into You album cover and some scenes from her Live à Paris concert. It was made for the single version and it was directed by Nigel Dick. The second version was made for the UK market with the same white T-shirt scenes but adding footage of a young couple in love at Christmas time, instead of scenes from Dion's concert. This was made for the album version. Finally, a live music video was released in March 1997 in North America (from the 1996 concert in Montreal).
Dion recorded also a Spanish version of "All by Myself," called "Sola Otra Vez" (English: By Myself Again). It was added to the Falling into You Latin American/Spanish edition, and as a B-side to other singles from that album. This version became available worldwide on Dion's later compilation The Collector's Series, Volume One. The CD single was released in 1996 in Brazil only. Dion's "Sola Otra Vez" was selected the number one Spanish language cover of an English pop song by TheSpanishVersion.Org.
The "All by Myself" single became one of Dion's biggest hits in the United States, reaching number 1 on the Hot Adult Contemporary Tracks (for three weeks) and the Latin Pop Airplay (two weeks). It peaked at number 4 on the Billboard Hot 100 (number 7 on the Billboard Hot 100 Airplay and number 5 on the Hot 100 Singles Sales). It was also a top 10 hit in France, United Kingdom, Wallonia in Belgium and the Republic of Ireland. In Canada, "All by Myself" was released as a promotional single only, hitting number 1 on the Adult Contemporary Chart. "All by Myself" was certified gold in the U.S. (500,000), and silver in the UK (200,000) and France (165,000).
Dion's cover received mixed to positive reviews. New York Times editor Stephen Holden wrote that the remake, along with "Because You Loved Me," "are the strongest cuts on an album crammed with formulaic romantic bombast." Music.uk.launch.yahoo.com editor, Dan Leroy, wrote: "Trying to out-emote Eric Carmen was almost crazy enough to work."Entertainment Weekly editor Chuck Eddy said:" ...But only in her desolate cover of Eric Carmen's All by Myself does she truly crash through the glass ceiling of passion."