Rawle landed his first major role in 1973 as Billy in the TV version of Keith Waterhouse and Willis Hall's Billy Liar. In 1984 he appeared in the Doctor Who story Frontios as the character Plantaganet. He appeared in Faith in the Future on ITV from 1995–1998. In 2004, Rawle began appearing in the ITV series Doc Martin as Roger Fenn. The actor went on to make a guest appearance in the fourth episode of the fourth series of New Tricks as Lawyer Jonathan Blunt. The following year, he starred in the fourth series of Spooks as the Home Secretary. He also appeared in Ultimate Force – "Never Go Back" alongside Ross Kemp.

Rawle has provided numerous narrations including A Bear Called Paddington, three series of the Duchess of York's Budgie the Little Helicopter, Stephen Hawking's Universe and Tom Fort's The Grass is Always Greener for BBC Radio 4. Rawle's writing credits include The Young Poisoner's Handbook in 1995 and Who Goes There?

Rawle played Amos Diggory, father to Cedric Diggory (Robert Pattinson), in Harry Potter and the Goblet of Fire. 2008 saw Rawle play Gilbert Murray in the National Theatre's production of Tony Harrison's play Fram. The following year, the actor guested in The Bill and appeared in The Sarah Jane Adventures on CBBC. During 2010, Rawle joined the cast of Hollyoaks in the role of Silas Blissett. He stated that he was delighted to be playing such a sinister character. He has won various awards for his portrayal of Silas.

In October 2012, it was announced Rawle had joined the cast of Doctors as Rory Bishton, "a road sweeper with something to hide." Rawle made his screen debut as Rory in early 2013. He previously appeared in the show in 2004.