Göran Bror Benny Andersson was born in the Vasastan district of Stockholm to civil engineer Gösta Andersson (1912–1973) and his wife Laila (1920–1971). His sister Eva-Lis Andersson followed in 1948. Andersson’s musical background comes from his father and grandfather (Efraim); they both enjoyed playing the accordion, and at six, Benny got his own. His father and grandfather taught him Swedish folk music, traditional music, and schlager. The first records Benny bought were “Du Bist Musik” by Italian schlager singer Caterina Valente and Elvis Presley’s “Jailhouse Rock”. He was especially impressed by the flip side, “Treat Me Nice”, as this featured a piano. This variety of different kinds of music influenced him through the years.

Andersson was engaged to Christina Grönvall. In 1963, they had a son, Peter, and in 1965, a daughter, Heléne. Both children were given their mother’s surname. They split in 1966 and Christina kept custody of the children as Andersson was then at the peak of his Hep Stars’ success. In the 1990s, Peter formed One More Time, a group that enjoyed European success with the ABBA-like “Highland” and, later, as Sweden’s entry to the Eurovision Song Contest 1996.

At ten, Andersson gained his own piano and taught himself to play. He left school at 15 and began to perform at youth clubs. This is when he met his first girlfriend Christina Grönvall, with whom he had two children: Peter (born 1963) and Heléne (born 1965). In early 1964, Benny and Christina joined “Elverkets Spelmanslag” (“The Electricity Board Folk Music Group”); the name was a punning reference to their electric instruments. Their repertoire consisted mainly of instrumentals, including “Baby Elephant Walk”; he also wrote his first songs.

In October 1964 he joined the Hep Stars as keyboardist and they made a breakthrough in March 1965 with their hit “Cadillac”, eventually becoming the most celebrated of the Swedish 1960s pop bands. Andersson consolidated his place as the band’s keyboardist and musical driving force as well as a teen idol. The band performed mostly covers of international hits, but Andersson soon started writing his own material, and gave the band the classic hits “No Response”, “Sunny Girl”, “Wedding”, “Consolation”, “It’s Nice To Be Back” and “She Will Love You” amongst others.

Andersson met Björn Ulvaeus in June 1966, and the two men started writing songs together, their first being “Isn’t It Easy To Say”, eventually recorded by the Hep Stars. He also had a fruitful songwriting collaboration with Lasse Berghagen, with whom he wrote several songs and submitted “Hej, Clown” for the 1969 Melodifestivalen – the Swedish Eurovision Song Festival finals. The song finished in second place. During this contest, he met vocalist Anni-Frid Lyngstad, and they soon became a couple. Around the same time, his songwriting companion Ulvaeus met vocalist Agnetha Fältskog.

The group’s breakthrough came with winning the Eurovision Song Contest for Sweden with “Waterloo” on 6 April 1974. During the next eight years, Andersson (together with Ulvaeus) wrote music for and produced eight studio albums with ABBA. The group achieved great success globally and scored a chain of No. 1 hits.

Andersson was engaged to Anni-Frid Lyngstad of ABBA for about nine years. They married on 6 October 1978 but separated on 26 November 1980 and divorced in 1981.

He married Swedish TV presenter Mona Nörklit in 1981 and had a son, Ludvig (born January 1982), who has since followed in his father’s footsteps in forming his own band.

After ABBA, Andersson continued writing music with Ulvaeus. Their first project was the stage musical Chess, written with Tim Rice. The Chess concept album – with vocals by Elaine Paige, Barbara Dickson, Murray Head and Swedes Tommy Körberg and Björn Skifs – was released in October 1984, selling two million copies worldwide. The Paige/Dickson duet “I Know Him So Well” became a major UK No. 1 hit, and Murray Head’s “One Night in Bangkok” gave Andersson/Ulvaeus a US No. 3 hit.

In 1985, Andersson produced and released an album with brother and sister Anders and Karin Glenmark, featuring new songs by Andersson/Ulvaeus. The duo named themselves Gemini, and a second album with more music by Björn and Benny was released in April 1987, containing the big hit “Mio My Mio”; also to be found on the soundtrack to the film Mio in the Land of Faraway, for which Andersson co-produced the music.

Chess was staged in London’s West End Prince Edward Theatre in May 1986 and received mixed to positive reviews, running for about three years. A revised staging on Broadway in April 1988 received poor reviews, running for two months.

In 1987, Andersson released his first solo album Klinga Mina Klockor (“Chime, My Bells”). All the music was written by and performed by himself on accordion, backed by the Orsa Spelmän (Orsa Folk Musicians) on fiddles. A second solo album followed: November 1989.

In 1987, Andersson wrote music and co-produced the soundtrack with Anders Eljas for the film Mio in the Land of Faraway, based on Swedish author Astrid Lindgrens Mio, My Son. The title song became a huge hit in Sweden for Gemini.

In 1990, Andersson scored a Swedish No. 1 hit with “Lassie”, sung by female cabaret group Ainbusk, for whom he also wrote the Svensktoppen hits “Älska Mig” and “Drömmarnas Golv”. He decided to produce an album with Josefin Nilsson from this quartet, resulting in the 1993 English-language album Shapes, featuring ten new Andersson/Ulvaeus compositions.

In 1992, he wrote the introduction melody for the European football championship, which was organised by Sweden that year.

From the late 1980s, Andersson had worked on an idea for an epic Swedish language musical based on his affection for traditional folk music, and in October 1995, Kristina från Duvemåla premiered in Sweden. The musical was based on The Emigrants novels by Swedish writer Vilhelm Moberg. The musical ran successfully for almost five years, before closing in June 1999. An English-language version, simply titled Kristina, was staged in concert at Carnegie Hall in New York City for two nights in September 2009, yielding a live recording, and at the Royal Albert Hall for one night in April 2010.

In 2000, he wrote the music for fellow Swede (no relation) Roy Andersson’s film Songs from the Second Floor (the music later re-recorded, featuring new lyrics, with BAO! with vocals by Helen Sjöholm). He also wrote the theme for Roy Andersson’s next film, You, the Living, from 2007.

During his post-ABBA career Andersson won four Swedish Grammis awards, and together with Ulvaeus received the “Special International” Ivor Novello award from ‘The British Academy of Composers and Songwriters’, twice “The Music Export Prize” from the Swedish Ministry of Industry and Trade (2008), as well as the “Lifetime Achievement” award from the Swedish Music Publishers Association (SMFF). In 2002, Andersson was given an honorary professorship by the Swedish Government for his “ability to create high-class music reaching people around the world”.

For the 2004 semi-final of the Eurovision Song Contest, staged in Istanbul thirty years after ABBA had won the contest in Brighton, Benny appeared briefly in a special comedy video made for the interval act, entitled “Our Last Video”. Each of the four members of the group appeared briefly in cameo roles, as did others such as Cher and Rik Mayall. The video was not included in the official DVD release of the Eurovision Contest, but was issued as a separate DVD release. It was billed as the first time the four had worked together since the group split; however, Frida’s appearance was filmed separately.

In 2007, he was elected a member of Royal Swedish Academy of Music, and in 2008 received an Honorary Doctorate from the Stockholm University Faculty of Humanities for contributing importantly both to the preservation and the growth of the Swedish folk music tradition.

A film version of Mamma Mia! premiered on 18 July 2008. In April/May 2007, Andersson worked on the film soundtrack, re-recording the ABBA songs with musicians from the original ABBA recording sessions. Mamma Mia! The Movie has become the most successful film musical of all time, and the biggest-selling DVD ever in the UK.

In the spring of 2009, Andersson also released a single recorded by the staff at his privately owned Stockholm hotel Hotel Rival, titled “2nd Best to None”, accompanied by a video showing the staff at work. In 2008, Andersson and Ulvaeus wrote a song for Swedish singer Sissela Kyle, titled “Jag vill bli gammal” (“I Wanna Grow Old”), for her Stockholm stage show “Your Days Are Numbered”, which was never recorded and released but did get a TV performance. Ulvaeus also contributed lyrics to ABBA’s 1976 instrumental track “Arrival” for Sarah Brightman’s cover version recorded for her 2008 album A Winter Symphony. New English lyrics have also been written for Andersson’s 1999 song “Innan Gryningen” (then also named “Millennium Hymn”), with the new title “The Silence of the Dawn” for Barbara Dickson was performed live, but not yet recorded and released. In 2007, they wrote the new song “Han som har vunnit allt” (“He Who’s Won It All”) for actor and singer Anders Ekborg. Ulvaeus wrote English lyrics for two older songs from Andersson’s solo albums I Walk with You Mama (“Stockholm by Night”, 1989) and After the Rain (“Efter regnet”, 1987) for opera singer Anne Sofie Von Otter, for her Andersson tribute album I Let the Music Speak. Barbara Dickson recorded an Ulvaeus and Andersson song called “The Day The Wall Came Tumbling Down”; the song eventually was released by Australian Mamma Mia! musical star Anne Wood’s album of ABBA covers, Divine Discontent. As of October 2012, Ulvaeus had mentioned writing new material with Andersson for a BAO Christmas release (also mentioned as a BAO box), and Andersson is busy writing music for a Swedish language obscure musical, Hjälp Sökes (“Help is Wanted”) together with Kristina Lugn and Lars Rudolfsson, premiering 8 February 2013. Andersson has also written music for a documentary film about Olof Palme, re-recording the track “Sorgmarch” from his last album as a theme throughout the film. The song “Kärlekens Tid”, recorded 2004 by Helen Sjöholm with BAO, has also been performed in concert in English (lyrics by Ylva Eggehorn) by opera baritone Bryn Terfel. On 15 April 2013, it was officially announced by the EBU and the SVT that Andersson, along with Ulvaeus and the late Stockholm based DJ and record producer Avicii, had composed the anthem for the 2013 Eurovision Song Contest. The song was performed for the first time in the Final on 18 May.

For a compilation album of the Glenmark duo Gemini, Andersson had Björn Ulvaeus write new Swedish lyrics for the re-recording of two songs from 1984 and 1987. Andersson and Ulvaeus have continuously been writing new material; most recently the two wrote seven songs for Andersson’s BAO 2011 album O Klang Och Jubeltid, performed as usual by vocalists Sjöholm, Körberg and Moreus. In July 2009, BAO, now named “The Benny Andersson Band”, released their first international record, the album The Story of a Heart. It was a compilation of 14 tracks from Andersson’s five Swedish-language releases between 1987 and 2007, including five songs now recorded with lyrics by Ulvaeus in English, and the new title song premiered on BBC2’s Ken Bruce Show. A Swedish-language version of the title track, “Sommaren Du Fick” (“The Summer You Got”), was released as a single in Sweden prior to the English version, with vocals by Helen Sjöholm.

On 15 March 2010, Andersson appeared on stage in New York with former wife Anni-Frid Lyngstad to accept ABBA’s award of induction into the Rock and Roll Hall of Fame. During his acceptance speech he reflected on the important influence of traditional European music and the melancholy of the Swedish soul on ABBA’s brand of pop music. “If you live in a country like Sweden, with five, six months of snow, and the sun disappears totally for like two months, that would be reflected in the work of artists,” he said. “It’s definitely in the Swedish folk music, you can hear it in the Russian folk songs, you can hear in the music from Jean Sibelius or Edvard Grieg from Norway, you can see it in the eyes of Greta Garbo and you can hear it in the voice of Jussi Björling. And you can hear in the sound of Frida and Agnetha on some of our songs too.”

In 2012, he received an Honorary Doctorate of Philosophy from the Luleå Tekniska Universitet Faculty of Humanities and Social Sciences.

Andersson won the Swedish “Guldbaggen” award in 2012 as composer of the music for the film “Palme”.

A new album of Andersson compositions presented in a choral style was released on 18 September 2015. “Kärlekens Tid” was produced in Andersson’s Mono Music studio, under the direction of choirmaster Gustaf Sjökvist, who died before the album’s release. Gustaf Sjökvists Choir, conducted by Cecilia Rydinger Alin, performed two concerts at Skeppsholmen on 20 September, featuring Benny Andersson on piano. The album includes songs in Swedish and English from a range of Andersson’s projects, such as Chess, Kristina and BAO.

In November 2018, Deutsche Grammophon released Piano, a collection of ABBA tunes, tunes from Chess and original compositions all played by Andersson on solo piano.