He’ll replace Dennis Waterman who is leaving at the start of the show’s 12th series in what producers promise will be “an explosive” two part story.
Waterman’s exit marks the departure of the last remaining cast member.
In recent years Alun Armstrong, James Bolam and Amanda Redman have all left the show.
Lamb will join current stars Tamzin Outhwaite, Denis Lawson and Nicholas Lyndhurst in the second episode of the new run as as Ted Case, an ex-copper who becomes UCOS’s latest recruit.
He says: “I’m thrilled to have been asked to join such a well-loved show. The writing and the cast are top notch and I’m really looking forward to getting started.”
New Tricks is a BBC One Network drama made by Headstrong Pictures.
The executive producers are Myar Craig-Brown for Headstrong and Polly Hill for the BBC with Huw Kennair-Jones producing.
Myar Craig-Brown, Headstrong Pictures said: “Larry is a fantastic addition to the show and Ted Case will slot in perfectly with Sacha, Steve and Dan in the UCOS team.
“The stories for series 12 are absolutely classic New Tricks – a mix of gripping whodunits solved by witty, likeable characters that the audience can root for and identify with.”
Polly Hill, BBC Head of Independent Drama, says: “Larry is a brilliant and talented actor, he is a fantastic recruit for UCOS and we look forward to seeing the new team in action.”