In the role, Chapman will oversee all film output and production processes for the agency, producing campaigns for clients including Bacardi, Diet Coke, Samsung and Cow & Gate.
He will take on some of the responsibilities currently under the remit of the director of operations, Jonathan Davis, and will report to Neil Dawson, the co-founder and executive creative director.
Chapman spent two years at AMV BBDO, producing work for National Lottery Good Causes, which triumphed at the British Arrows and International Andy Awards. He was behind the latest two Guinness brand ads, "clock" and "cloud", and previously spent six years at Bartle Bogle Hegarty as a senior producer.
BETC London has also hired the creatives Sigrid Egedal and Oliver Rimoldi from Adam & Eve/DDB. The pair will work across all agency accounts.
Dawson said: "Olly brings enormous firepower to our film capabilities, while Siggi and Oli are an exciting, effervescent, talented team on the rise."