Cheetham joins in November and has been tasked with shaking up the agency's creative output and weaving together its full-service capabilities.
He joins after four years at Leo Burnett, where he began as ECD of Arc in 2012. He then became ECD of Leo Burnett's activation specialism after the agency streamlined its its operations last October.
Cheetham led Leo Burnett's The Co-operative Group win in March and was the creative brain behind the NSPCC's "I saw your willy" campaign. He also worked with Samsung, RNLI, Procter & Gamble and Molson Coors during his four years at Leo Burnett.
Luke Mugliston, chief executive at The Gate, said: "Beri is a game changer. His track record of taking solid agencies and quickly building their creative reputation is just what we’re looking for. He comes with exactly the right collaborative attitude, enthusiasm and new business focus."