The Gift sold 3.7 million copies abroad compared with the six million shifted by her debut I Dreamed A Dream.
Boyle's record was followed by Sade's Soldier of Love, with 2.3 million, and Mumford and Sons' Brits-winning album Sigh No More, which sold 1.3 million.
Muse's The Resistance, released in 2009, was fourth with a million copies.
Phil Collins' Motown covers album Going Back, Plastic Beach by Gorillaz, and James Blunt's Some Kind of Trouble all sold 900,000 copies overseas.
Take That's Progress - the top-selling album in the UK last year with sales of 1.8 million - clocked up a further 800,000 copies abroad.
Lungs, by Florence and the Machine, also sold 800,000 copies, while Rod Stewart's latest Great American songbook collection shifted 700,000 copies.
The top four albums in the Music Week list scored top three placings in the US Billboard 200 album chart.
Fifth-placed Going Back, by Phil Collins, reached 34 in the US chart but was a huge hit across Europe.
Susan Boyle scored the most successful album overseas by a UK artist for a second year running, research by Music Week magazine suggests.