Donnelly, who enjoyed one of the longest, most prolific collaborations in the business with the late Ken Grimshaw, joins at the end of the month to partner John Peacock.
The move reunites Donnelly with VCCP's creative director, Rooney Carruthers.
The pair previously worked together in the late 80s at Abbott Mead Vickers BBDO.
Carruthers said: "John is an incredible talent, but he's also an extremely nice guy, one of a rare breed. He will give us another dimension."
Donnelly spent the past ten years at JWT, where he and Grimshaw were renowned for creating campaigns in notoriously difficult categories.
They first linked up at CDP Aspect in 1981 and later moved to KMP, which became CME KHBB. In 1985, they relocated to TBWA, before AMV beckoned in 1986.
During four years at the agency, the pair worked on key accounts including Yellow Pages and The Economist, for which Donnelly won a silver at the Campaign Poster Awards.
Donnelly said: "The combination of working with Rooney and John was just irresistible. It's a small agency but it's full of energy."