The Britain's Got Talent star's record-breaking second album The Gift sold 3.7 million copies outside of the UK, Music Week research reveals. Boyle's debut album I Dreamed A Dream achieved the same success with over six million units being sold in 2009.
Sade's Soldier Of Love was second in the list with sales of 2.3 million, ahead of Mumford & Sons' Sigh No More which sold 1.3 million copies.
Muse's The Resistance achieved sales of 1 million, while Phil Collins's Going Back, Gorillaz's Plastic Beach and James Blunt's Some Kind Of Trouble all sold 900,000 units in markets outside of the UK.
Take That's Progress added 800,000 copies to its UK total of 1.8 million.
The top four highest-selling albums all held a top three placing in the US Billboard 200 album chart at some point last year.