Björn Ulvaeus, 79, Anni-Frid Lyngstad, 78, Agnetha Fältskog, 74, and Benny Andersson, 77, were honoured at the Royal Palace in Sweden’s capital Stockholm.
The group — who won the Eurovision Song Contest with Waterloo in 1974 — got the Order of the Vasa for their “very outstanding efforts in Swedish and international music life”.
It was the first time the order has been handed out since reforms to the Swedish honours system 50 years ago.
Abba, who have sold more than 150million records worldwide, have not been seen together since the 2022 launch of their virtual Abba Voyage concerts at a purpose-built arena in Stratford, East London.
Asked at the time whether there would be any further projects from the band, Benny said: “It’s a no. Nothing is going to happen after this.”
Notably, this is not the first time Abba star Anni-Frid has rubbed shoulders with the upper class.
In 1992 she wed Prince Heinrich Ruzzo Reuss, Count of Plauen.
She became the Dowager Princess of Reuss when Heinrich Ruzzo died of lymphoma in October 1999.
After his death, she started seeing Brit aristocrat Henry Smith, 5th Viscount Hambledon.
Anni-Frid has taken a hiatus from music since 2005, preferring to now be involved in charity work.