The news comes after the former Public Enterprise Minister outsold all Irish rivals.
Since it was published in October, 'Just Mary – A Memoir' has racked up sales of more than 12,000 copies here.
"I'm so lucky that people are buying the book in spades. All I can say is, and rather immodestly, is that I think it's a good story," Ms O'Rourke, left, told the Irish Independent.
Along with the cut and thrust of political life, Ms O'Rourke writes movingly in the book about her final conversation with her nephew, former Finance Minister Brian Lenihan, before he passed away from cancer aged 52 in 2011.
"My book reflects the sorrows and joys that everybody experiences in life.," she said. Revealing that she had yet to define the subject of her next book, she ruled out penning a novel. "I find that real life is racier than the raciest novels so it won't be a novel," said Ms O'Rourke.
Her sales of 12,423 up to Christmas were well ahead of former President Mary Robinson's memoir 'Everything Matters' which sold 9,175, and former Presidential candidate Senator David Norris' autobiography 'A Kick against the Pricks'. which achieved sales of 2,171.
Meanwhile, former South African Ambassador Melanie Verwoerd has had sweet revenge on panto dame Twink with her memoir 'When We Dance' selling 4,337 copies ahead of Adele King's autobiography 'Unzipped' which sold 1,973. Twink described Ms Verwoerd's decision to write the book, some of which dealt with the last days of her friend the late broadcaster Gerry Ryan, as "gut-wrenchingly awful".