The highly anticipated concert from the Swedish pop superstars - Bjorn Ulvaeus, Benny Andersson, Agnetha Faltskog and Anni-Frid Lyngstad - features younger 'Abba-tars' of the group performing songs from their back catalogue with a live 10-piece band.
The king and queen of Sweden, Carl XVI Gustaf and Silvia, were among the star-studded guestlist on the night, along with Kylie Minogue, Keira Knightley and London Mayor Sadiq Khan.
Speaking on the red carpet outside a purpose-built stadium at the Queen Elizabeth Olympic Park in east London, Lyngstad said she was most looking forward to seeing the band perform Abba's worldwide smash hit Mamma Mia.
"The most exciting thing about this project was to come together as a group again after so many years not doing anything as a band," she said.
Andersson admitted he expected himself to cry during the concert, saying: "Oh definitely, all the time."
On why the band had chosen the UK for the launch of their live-performance project, Ulvaeus said: "The UK has always been close to our hearts and the Brits have always taken us to their heart, and also the infrastructure for a huge project like this is here in London - so many reasons."
The Abba-tars were created through months of motion-capture and performance techniques with the four band members and an 850-strong team from Industrial Light and Magic, the company founded by Star Wars director George Lucas, in its first foray into music.
The digital band delivered a hit-filled set featuring tracks such as Knowing Me, Knowing You, Fernando and, of course, Mamma Mia while the real-life Abba watched on from the stands.
In a nod to the venue's east London location, Andersson's Abba-tar kicked off a rendition of their song SOS by playing the theme tune to popular TV soap EastEnders on the piano.
Numerous outfit changes saw the band don sparkly dresses and cowboy boots, denim jumpsuits and futuristic space suits featuring neon detailing.
During their version of Waterloo, Ulvaeus jokingly recalled how the UK jury awarded them zero points at the Eurovision Song Contest in 1974.
The band closed with The Winner Takes It All before the real-life Abba took to the stage, flanked by the show's director and producer, and embraced each other to loud cheers and applause.
Abba were catapulted to worldwide success after winning Eurovision with Waterloo when the event was held in the English city of Brighton in 1974.
They have since sold more than 400 million albums and singles worldwide, and enjoyed six No.1 singles in Australia in the mid-1970s.
The popular quartet parted ways after last performing together in 1982 following a successful 10-year stint.
In 2018 they announced they had recorded new material, which arrived in November that year.
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