He was born in Ashbourne, Meath and was educated at Terenure College in Dublin and subsequently at University College Dublin. He praticed cases including those involving defamation and personal injury.
Condon was called to the Bar in 1944 andbecame a senior counsel n 1959. He was appointed as attorney general, serving under Taoiseach Sean Lemass. He remained in office under Lemass's successor, Jack Lynch. He argued on behalf of he State during the 1970 Arms Trial which involved future Taoiseach Charles Haughey.
In 1972 he helped draft legislation that set up the Special Criminal Court.
In 1997 Condon appeared before the Moriarty tribunal in which he sided with Haughey challenging the powers of the trubunal.