The singer's second album 21 has sold over 4,274,300 copies in the UK as of this morning (May 3), which is 500 sales ahead of Michael Jackson's Thriller.
"To add to her many landmark records, Adele's achievement in overtaking Thriller in the all-time sales list is truly remarkable," comments the Official Charts Company's managing director Martin Talbot.
"Thriller has long been recognised as one of the most iconic albums of all time - there is now no doubt that 21 can be spoken of in the same breath."
Since its release in the UK in January 2011, Adele's 21 has spent 65 weeks in the Top 10, with 23 of those weeks at number one.
It has outsold Amy Winehouse's Back To Black to become the highest-selling UK album of the 21st century and won Adele six Grammys and two Brit Awards.
The UK's five highest-selling albums of all-time are as follows:
1. Queen: Greatest Hits
2. The Beatles: Sgt Pepper's Lonely Hearts Club Band
3. ABBA: Gold: The Greatest Hits
4. Oasis: (What's The Story) Morning Glory?
5. Adele: 21
Watch the music video for Adele's 'Rolling In The Deep' below: