At first, Lyngstad was hesitant to perform with her boyfriend Benny Andersson, his best friend Björn Ulvaeus and his wife, Agnetha Fältskog.
Their first project together in the winter of 1970–1971 was the cabaret act Festfolket, which was not a success.
The following year, Lyngstad toured with Lasse Berghagen, while the other three future ABBA members started performing together on a regular basis.
Eventually, she rejoined the ensemble.
Andersson and Ulvaeus were busy producing other artists, but soon discovered the qualities of Lyngstad's and Fältskog's voices combined; thus, the band was formed initially as Björn & Benny, Agnetha & Anni-Frid, later renamed ABBA.

Possessing a wide mezzo-soprano vocal range, according to both Ulvaeus and herself, Lyngstad sang solo parts in the following ABBA songs: "Andante, Andante", "Cassandra", "Fernando", "Gonna Sing You My Lovesong", "I Am the City", "I Have a Dream", "I Let The Music Speak", "On Top of Old Smokey", "I Wonder (Departure)", "The King Has Lost His Crown", "Knowing Me, Knowing You", "Like an Angel Passing Through My Room", "Lovers (Live a Little Longer)", "Me and Bobby and Bobby's Brother", "Me and I", "Money, Money, Money", "The Name Of The Game", "One Man, One Woman", "Our Last Summer", "Put On Your White Sombrero", "Should I Laugh or Cry", "Super Trouper", "Tropical Loveland",  "The Visitors", "The Way Old Friends Do" and "When All Is Said And Done".

Lyngstad clearly enjoyed the spotlight more than the other three members of ABBA.
She liked to tour and to meet audience members one-to-one.
She took an active part in co-designing the famed ABBA costumes for their tours and TV performances.
Since the members of ABBA went their separate ways, Lyngstad has been the only one who openly regrets there has never been a reunion to date.

Her next solo album, in Swedish, was Frida ensam (Frida Alone), released in 1975 during the ABBA years, and produced by Benny Andersson.
This album includes her successful Swedish version of "Fernando", which stayed at the No.
1 spot in the Svensktoppen radio charts for 9 weeks, but was never released as a single.
The album was recorded between sessions of the ABBA albums Waterloo and ABBA.
Due to the activities of the group, the album took 18 months to record.
Frida ensam became an enormous commercial and critical success in Sweden, topping the Swedish album charts for six weeks and remaining in the charts for 38.
The album was mostly a collection of covers of songs by artists like the Beach Boys ("Skulle de' va' skönt"), 10cc ("Guld och gröna ängar") and David Bowie ("Liv på Mars?"),
receiving positive reviews from Melody Maker: "The album portrays Frida as a very strong and emotive singer and shows the true value of the music, that if sung properly and with enough feeling it transcends all language barriers".
This album was such a big success, it eventually went platinum.
At first, Lyngstad was hesitant to perform with her boyfriend Benny Andersson, his best friend Björn Ulvaeus and his wife, Agnetha Fältskog. Their first project together in the winter of 1970–1971 was the cabaret act Festfolket, which was not a success. The following year, Lyngstad toured with Lasse Berghagen, while the other three future ABBA members started performing together on a regular basis. Eventually, she rejoined the ensemble. Andersson and Ulvaeus were busy producing other artists, but soon discovered the qualities of Lyngstad's and Fältskog's voices combined; thus, the band was formed initially as Björn & Benny, Agnetha & Anni-Frid, later renamed ABBA.
Possessing a wide mezzo-soprano vocal range, according to both Ulvaeus and herself, Lyngstad sang solo parts in the following ABBA songs: "Andante, Andante", "Cassandra", "Fernando", "Gonna Sing You My Lovesong", "I Am the City", "I Have a Dream", "I Let The Music Speak", "On Top of Old Smokey", "I Wonder (Departure)", "The King Has Lost His Crown", "Knowing Me, Knowing You", "Like an Angel Passing Through My Room", "Lovers (Live a Little Longer)", "Me and Bobby and Bobby's Brother", "Me and I", "Money, Money, Money", "The Name Of The Game", "One Man, One Woman", "Our Last Summer", "Put On Your White Sombrero", "Should I Laugh or Cry", "Super Trouper", "Tropical Loveland",  "The Visitors", "The Way Old Friends Do" and "When All Is Said And Done".
Lyngstad clearly enjoyed the spotlight more than the other three members of ABBA. She liked to tour and to meet audience members one-to-one. She took an active part in co-designing the famed ABBA costumes for their tours and TV performances. Since the members of ABBA went their separate ways, Lyngstad has been the only one who openly regrets there has never been a reunion to date.
Her next solo album, in Swedish, was Frida ensam (Frida Alone), released in 1975 during the ABBA years, and produced by Benny Andersson. This album includes her successful Swedish version of "Fernando", which stayed at the No. 1 spot in the Svensktoppen radio charts for 9 weeks, but was never released as a single. The album was recorded between sessions of the ABBA albums Waterloo and ABBA. Due to the activities of the group, the album took 18 months to record. Frida ensam became an enormous commercial and critical success in Sweden, topping the Swedish album charts for six weeks and remaining in the charts for 38. The album was mostly a collection of covers of songs by artists like the Beach Boys ("Skulle de' va' skönt"), 10cc ("Guld och gröna ängar") and David Bowie ("Liv på Mars?"), receiving positive reviews from Melody Maker: "The album portrays Frida as a very strong and emotive singer and shows the true value of the music, that if sung properly and with enough feeling it transcends all language barriers". This album was such a big success, it eventually went platinum.
Anni-Frid Lyngstad