The writer picked up her first Booker trophy in 2009 for historical novel Wolf Hall and now the sequel, Bring Up the Bodies, has earned her a second.
Mantel, 60, becomes the first woman and first Brit to win the leading literary honour twice.
South African J.M. Coetzee and Peter Carey from Australia are the only other two-time winners.
Accepting her prize, Mantel quipped, "Well I don't know, you wait 20 years for a Booker Prize and two come along at once."
This year's (12) judging panel included Downton Abbey star Dan Stevens.
Mantel beat out the other shortlisted authors Will Self, Deborah Levy, Jeet Thayil, Alison Moore and Tan Twan Eng to claim the 2012 prize.