The Swedish superstars were joined by other musicians, homegrown actors, celebrities and guests for a private party at the Berns Salonger hotel in downtown Stockholm.
Officially, the band called it quits in 1982 and, despite a rumoured billion-dollar offer, the band refused to get back together for a reunion tour.
'It was absolutely amazing. A lot of emotions,' Lyngstad told Expressen of the reunion. 'We've made this journey throughout our history. Benny and Bjorn in particular. It's been very nostalgic.'
While there is no video footage of the bash, photos have circulated of the band embracing each other on stage.