Rory is the son of the late actor Roy Kinnear and actress Carmel Cryan, he has a sister, Kirsty and is the god-son of the late Michael Williams. He was educated at Tower House School and St Paul's School, read English at Balliol College, Oxford and then studied acting at LAMDA.

Kinnear has found particular acclaim for his performances in Phyllida Lloyd's production of Mary Stuart and as the outrageous Sir Foppling Flutter in The Man of Mode at the National Theatre, winning an Laurence Olivier Award and Ian Charleson Award for the latter.

Notable television roles include Mansfield Park, Five Days (2007), Silent Witness (2005), Judas (2004), The Second Coming (2003), Ultimate Force (2002) and Judge John Deed (2001).

In 2008 he portrayed Bill Tanner in the 22nd Bond movie, Quantum of Solace.