Her record label, Sony, says she is the first woman to reach the milestone achieved previously by the Beatles in 1969 and The Monkees in 1967.
Boyle said she has "never felt happier" than seeing "The Gift," match her first record's successful debut. "The Gift" reached No. 1 in the U.K. on Sunday and topped the U.S. charts Wednesday.
The eccentric Scot shot to international fame after her audition for the TV show "Britain's Got Talent" received more than 120 million views on YouTube. Boyle's first album, "I Dreamed A Dream," came out in 2009 and has sold more than 10 million copies.