Oliver was born in Tunbridge Wells, Kent, England. After studying there since 1997, he graduated from the Central School of Speech and Drama in 2000 and he soon appeared in the BBC big-budget adaptation of the classic novel Lorna Doone (2000). He followed this with another BBC Show, The Office (2001), where he appeared as "Ricky Howard" for the first series. Oliver was most recently seen starring in the Channel Four comedy series Green Wing (2004), Nathan Barley (2005) and The IT Crowd (2006). He also made an appearance in the highly anticipated Sharpe's Challenge (2006).