D'Arcy played in all of Ireland's 2006 Six Nations matches, he beat more defenders than any other player, and showed his talent. His return to top form continued during the autumn international series where his performances against Australia and South Africa contributed to back – to – back victories for the Irish team. D'Arcy usually played at inside centre for Leinster and Ireland with O'Driscoll outside him. He played in all of Ireland's 2007 Six Nations matches, he was nominated for RBS Six Nations Player of the Tournament in 2007. After sustaining a multiple fracture in his arm in the opening match of the 2008 Six Nations, versus Italy, D'Arcy missed the remainder of the season and only returned to Leinster in December 2008. He was a member of the victorious Ireland team that won the 2009 Six Nations Championship and Grand Slam.