Born in Paris, France, Gainsbourg was the son of Jewish Ukrainian migrants, Joseph Ginsburg (28 December 1898, in Kharkov, now Ukraine then Russian Empire  – 22 April 1971) and Olga (née Bessman; 1894 – 16 March 1985), who fled to Paris after the 1917 Russian Revolution. Joseph Ginsburg was a classically trained musician whose profession was playing the piano in cabarets and casinos; he taught his children - Gainsbourg and his twin sister Liliane - to play the piano.

He married Elisabeth "Lize" Levitsky on 3 November 1951 and divorced in 1957. He married a second time on 7 January 1964, to Françoise-Antoinette "Béatrice" Pancrazzi (b. 28 July 1931), with whom he had two children: a daughter named Natacha (b. 8 August 1964) and a son, Paul (born in spring 1968). He divorced Béatrice in February 1966.

Around 1957 he backed the Parisian "Cabaret Milord l'Arsouille" star, singer Michèle Arnaud.

Gainsbourg appeared in nearly 50 film and television roles. In 1960, he co-starred with Rhonda Fleming in the Italian film La rivolta degli schiavi (The Revolt of the Slaves) as Corvino, the Roman Emperor Massimiano's evil henchman. In 1968 he wrote music for and appeared as himself in Le Pacha directed by Georges Lautner. In 1969, he appeared in william Klein's pop art satire Mr. Freedom, and in the same year he starred with Jane Birkin in The Pleasure Pit. They acted together again in Cannabis the following year, and again in Seven Deaths in the Cat's Eye in 1973, and he also made a brief appearance with Birkin in Herbert Vesely's 1980 film, Egon Schiele – Exzess und Bestrafung. He co-starred alongside Birkin in the French film Slogan for which he wrote the title song "La Chanson de Slogan". Also with Birkin, he acted in the French-Yugoslav film Devetnaest djevojaka i jedan mornar (fr) (19 girls and one Sailor) where he played a role of a partisan.

By the time the yéyés arrived in France, Gainsbourg was 32 years old and was not feeling very comfortable: he spent much time with Jacques Brel or Juliette Greco but the public and critics rejected him, mocking his prominent ears and nose. During this period, Gainsbourg began working with Greco, a collaboration that lasted throughout the 'Left Bank' period culminating in the song La Javanaise in the fall of 1962.

He performed a few duets in 1964 with the Artist Philippe Clay, with whom he shared some resemblance. Around this time, Gainsbourg met Elek Bacsik. He pleased Gainsbourg, despite knowing that such a sound would not allow him access to success. The album sold only 1,500 copies. The decision was taken right upon leaving the studio: "I'll get into hack work and buy myself a Rolls". Still, his next album, Gainsbourg Percussions, inspired by the rhythms and melodies of Miriam Makeba and Babatunde Olatunji, was a world away from the yéyé wave, on the scene which was to become a key to the Gainsbourg fortune.

More success began to arrive when, in 1965, his song Poupée de cire, poupée de son was the Luxembourg entry in the Eurovision Song Contest. Performed by French teen and charming singer France Gall, it won first prize. The song was recorded in English as "A Lonely Singing Doll" by British teen idol Twinkle.

In 1967 Serge Gainsbourg appeared as a Dancer along with Jean Yanne and Sacha Distel in the Sacha Show with Marie Laforet singing 'Ivan, Boris & Moi'.

In mid-1968 Gainsbourg fell in love with the younger English singer and Actress Jane Birkin, whom he met during the shooting of the film Slogan. Their relationship lasted over a decade. In 1971 they had a daughter, the Actress and singer Charlotte Gainsbourg. Although many sources state that they were married, according to their daughter Charlotte this was not the case. Birkin left Gainsbourg in 1980.

The Parisian house in which Gainsbourg lived from 1969 until 1991, at 5 bis Rue de Verneuil, remains a celebrated shrine, with his ashtrays and collections of various items, such as police badges and bullets, intact. The outside of the house is covered in graffiti dedicated to Gainsbourg, as well as with photographs of significant figures in his life, including Bardot and Birkin.

Histoire de Melody Nelson was released in 1971. This concept album, produced and arranged by Jean-Claude Vannier, tells the story of a Lolita-esque affair, with Gainsbourg as the narrator. It features prominent string arrangements and even a massed choir at its tragic climax. The album has proven influential with artists such as Air, David Holmes, Jarvis Cocker, Beck and Dan the Automator.

In 1975, he released the album Rock Around the Bunker, an album written entirely on the subject of National Socialism. Gainsbourg used black comedy, as he and his family had suffered during World War II, being forced to wear the yellow star as the mark of a Jew. Rock Around the Bunker belonged to the mid-1970s "retro" trend.

In Jamaica in 1979, he recorded "Aux Armes et cætera", a reggae version of the French national anthem "La Marseillaise", with Robbie Shakespeare, Sly Dunbar and Rita Marley. Following harsh and anti-semitic criticism in right-wing newspaper Le Figaro by Charles de Gaulle biographer Michel Droit, his song earned him death threats from right-wing veteran Soldiers of the Algerian War of Independence, who were opposed to their national anthem being arranged in reggae style. In 1979, a show had to be cancelled, because an angry mob of French Army parachutists came to demonstrate in the audience. Alone onstage, Gainsbourg raised his fist and answered "The true meaning of our national anthem is revolutionary" and sang it with the audience. The Soldiers joined them, a scene enjoyed by millions as French TV news broadcast it, creating more publicity. Shortly afterward, Gainsbourg bought the original manuscript of "La Marseillaise". He replied to his critics that his version was closer to the original as the manuscript shows the words "Aux armes et cætera..." for the chorus. This album, described by legendary Drummer Sly Dunbar as "Perhaps the best record he ever played on" was his biggest commercial success, including major hits Lola Rastaquouère, Aux Armes Et Cætera and a French version of Sam Theard's jazz classic You Rascal You entitled Vieille Canaille. Rita Marley and the I-Three would record another controversial reggae album with him in 1981, Mauvaises nouvelles des étoiles. Bob Marley was furious, when he discovered that Gainsbourg made his wife Rita sing erotic lyrics. Posthumous new mixes, including dub versions by Soljie Hamilton and versions of both albums by Jamaican artists were released as double "Dub Style" albums in 2003, to critical praise in France as well as abroad and to international commercial success. Although belatedly, Aux Armes Et Cætera – Dub Style and Mauvaises Nouvelles Des Étoiles – Dub Style further posthumously established Gainsbourg as an influential icon in European pop music.

After a turbulent 13-year relationship, Jane Birkin left Gainsbourg. In the 1980s, near the end of his life, Gainsbourg became a regular figure on French TV. His appearances seemed devoted to his controversial sense of humour and provocation. In March 1984, he burned three-quarters of a 500 French franc bill on television to protest against taxes rising up to 75% of income.

In 1982, Gainsbourg wrote an album for French rocker Alain Bashung, Play blessures. The album, although now considered a masterpiece by French critics, was a commercial failure.

He would show up drunk and unshaven on stage: in April 1986, on Michel Drucker's live Saturday evening television show Champs-Élysées, with the American singer Whitney Houston, he objected to Drucker's translating his comments to Whitney Houston and in English stated: "I said, I want to fuck her" - Drucker insisted this meant "He says you are great..." The same year, in another talk show interview, he appeared alongside Catherine Ringer, a well known singer who had appeared in pornographic films. Gainsbourg spat out at her, "You're nothing but a filthy whore, a filthy, fucking whore".

By December 1988, while a judge at a film festival in Val d'Isère, he was extremely intoxicated at a local theatre where he was to do a presentation. While on stage he began to tell an obscene story about Brigitte Bardot and a champagne bottle, only to stagger offstage and collapse in a nearby seat. Subsequent years saw his health deteriorate. He had to undergo liver surgery but denied any connection to cancer or cirrhosis. His appearances and releases became sparser as he had to rest and recover in Vezelay. During these final years, he released Love on the Beat, a controversial electronic album with mostly sexual themes in the lyrics and his last studio album, You're Under Arrest, presented more synth-driven songs.

Gainsbourg died on 2 March 1991 of a heart attack, a month shy of his 63rd birthday. He was buried in the Jewish section of the Montparnasse Cemetery in Paris. French President François Mitterrand said of him, "He was our Baudelaire, our Apollinaire ... He elevated the song to the level of art."

Throughout his career, Gainsbourg wrote the soundtracks for nearly 60 films and television programs. In 1996, he received a posthumous César Award for Best Music Written for a Film for Élisa, along with Zbigniew Preisner and Michel Colombier.

Since his death, Gainsbourg's music has reached legendary stature in France. He has also gained a following in the English-speaking world, with numerous artists influenced by his arrangements. One of the most frequent interpreters of Gainsbourg's songs was British singer Petula Clark whose success in France was propelled by her recordings of his tunes. In 2003, she wrote and recorded La Chanson de Gainsbourg as a tribute to the Composer of some of her biggest hits. The majority of Gainsbourg's lyrics are collected in the volume Dernières nouvelles des étoiles.

In 2008, Paris' Cité de la Musique held the Gainsbourg 2008 exhibition, curated by sound Artist Frédéric Sanchez.

Comics Artist Joann Sfar wrote and directed a feature film titled Gainsbourg (Vie héroïque), which was released in France in 2010. Gainsbourg is portrayed by Eric Elmosnino and Kacey Mottet Klein. The film won three César Awards, including Best Actor for Elmosnino, and nominated for an additional eight.

His songs became increasingly eccentric during this period, ranging from the anti-drug Aux Enfants de la Chance, to the highly controversial duet with his daughter Charlotte named Lemon Incest. This translates as "Inceste de citron", a wordplay on "un zeste de citron" (a lemon zest). The title demonstrates Gainsbourg's love for puns – another Example of which is Beau oui comme Bowie, a song he gave to Isabelle Adjani.

His lyrical works incorporated a vast amount of clever word play to hoodwink the listener, often for humorous, provocative, satirical or subversive reasons. Common types of word play in his songs include mondegreen, onomatopoeia, rhyme, spoonerism, dysphemism, paraprosdokian and pun. Through the course of his career, Gainsbourg wrote over 550 songs, which have been covered more than 1,000 times by a wide range of artists. Since his death, Gainsbourg's music has reached legendary stature in France, and he is regarded as one of France’s most revered Musicians. He has also gained a cult following in the English-speaking world, with numerous artists influenced by his arrangements.