While on the road in southern Sweden in 1966, they encountered the Hep Stars, and Ulvaeus quickly became friends with the group's keyboard player, Benny Andersson.

In 1968, they composed two songs together: "A Flower in My Garden", recorded by Hep Stars, and their first real hit "Ljuva Sextiotal", performed by popular Swedish artist Brita Borg, for which Stig Anderson wrote lyrics.

Another hit came in 1969 with "Speleman", also recorded by Hep Stars.While filming a nostalgic schlager special for television in May 1969, Björn met eighteen-year-old future wife and singer-songwriter Agnetha Fältskog.

Polar artist Arne Lamberts Swedish version of "A Flower in My Garden" ("Fröken Blåklint") was one of Björn & Benny's first in-house productions.

The Hootenanny Singers entered Svensktoppen, the Swedish radio charts, in 1970 with "Omkring Tiggarn Från Luossa", a cover of an old folk-schlager song.

Björn was the guitar player in the band, but he also sang lead vocals in the following songs: People Need Love, Merry Go Round, Santa Rosa, Another Town Another Train, I Saw It in the Mirror, Love Isn't Easy (But It Sure Is Hard Enough), He Is Your Brother, Rock'n Roll Band, She's My Kind of Girl, Honey Honey, Sitting in the Palmtree, King King Song, Watch Out, Man in the Middle, Rock Me, Crazy World, Why Did It Have To Be Me?, Summer Night City, Does Your Mother Know, Two for the Price Of One.

After ABBA went on hiatus in 1982, Ulvaeus and Andersson created the musicals Chess, a collaboration with lyricist Tim Rice,[4] Kristina från Duvemåla (based on The Emigrants novels by Swedish writer Vilhelm Moberg), and Mamma Mia!

On 15 April 2013, it was officially announced by the EBU and the SVT that Ulvaeus and Andersson, with the late Swedish DJ and record producer Avicii, had composed the anthem for the 2013 Eurovision Song Contest.

[12] In April 2018, the four members issued a statement saying that during preparations for the tour, they had regrouped with Fuller in the studio and recorded two new songs, titled "I Still Have Faith in You" and "Don't Shut Me Down".

The new record, their first in 40 years, features ten tracks, including "I Still Have Faith In You" and "Don't Shut Me Down", which were first shown in the aforementioned livestream event and released as a double A-side single.

Since November 2021, Ulvaeus and British actor Ian McKellen have posted Instagram videos featuring the pair knitting Christmas jumpers and other festive attire.

[17] In October 2023, it was confirmed that Ulvaeus would be the keynote speaker for The Business Day at Bridlington Spa in the United Kingdom on Friday 7 June 2024.

Ulvaeus is expected to discuss the creation of ABBA Voyage, leadership, entrepreneurship, artificial intelligence (AI), Technology, Innovation, Meta Data and the complexity of business in the music industry.

[19] In 2021 whilst producing Voyage, Ulvaeus met Christina Sas, a product manager at Universal Music Group, and they began dating the following year.

[27][28][29][30] On 21 March 2024, all four members of ABBA were appointed Commander, First Class, of the Royal Order of Vasa by His Majesty King Carl XVI Gustaf of Sweden.

This was the first time in almost 50 years that the Swedish Royal Orders of Knighthood was bestowed on Swedes, also the 50th anniversary of ABBA winning the Eurovision Song Contest.