John Tams has had a successful career in the theatre in parallel with his singing career, often combining the two. At the National Theatre he worked as actor and musical director/composer on over 30 productions, including The Mysteries and Lark Rise to Candleford, many of which transferred to the West End or toured.

He played Rifleman Daniel Hagman in the TV series Sharpe, for which he was script associate, co-writing the score. He provided original music for The Grapes of Wrath at Chichester Festival Theatre. Back at the National Theatre, he was Songmaker for WarHorse, which has played to 8 million people in 11 countries around the world. He was nominated for an Olivier Award for the Best Sound along with his fellow team members Chris Shutt and Adrian Sutton.