Tennyson, 22, will challenge Walsh for his belt at the Copper Box Arena.
Known as 'The Assassin' he has a 16-1 record with 13 knockouts since turning pro in September 2012 and joined Warren's stable on Monday.
"It's massive, I feel this move could bring my career to the next level," Tennyson said.
"Beyond British title fights, I believe Frank Warren can bring me bigger and better titles in the future."
Tennyson is the mandatory challenger to Walsh after dispatching Antonio Horvatic inside a round in Belfast last month.
His British featherweight title fight is on the undercard of Billy Joe Saunders' first WBO middleweight world title defence against Ukraine's Max Bursak.
"I'm not expecting to go in and blow Ryan Walsh out of the water because he's a good fighter, and he's the British champion for a reason," said Tennyson.
"I'm going to go in and get the job done regardless, but I'm training for 12 rounds."
Belfast featherweight James Tennyson will fight Ryan Walsh for the British title in London on 30 April after signing with promoter Frank Warren.