Jackson, a board planner at AMV for the past four years, becomes the first senior management hiring by Chris Herd, the Bates managing director, since his arrival seven months ago.
He said: "Bates is now a very different place to what it was two years ago and Vanella's hiring is part of our efforts to keep that going. It's when people don't recognise us any more that we'll feel we've achieved something."
Jackson's departure from AMV comes in the wake of major changes within the agency's planning department, which is reducing in size and attempting to improve the quality of its offering to clients.
But Jackson insisted: "My departure, and what's happening at AMV, are a complete coincidence.
"I wanted to run a department and I'm not only impressed by Chris' 'can-do' attitude, but by Bates, which doesn't just talk about integration but actually does it."
The agency regards last year's capture of Sky - which has a reputation as a promiscuous client - as a key element in its recovery from a period beset by management turmoil and account losses.
Jackson, 41, began her career in 1981 at Hedger Mitchell Stark and has also worked at Young & Rubicam, Bartle Bogle Hegarty and Woollams Moira Gaskin O'Malley.
She later spent four years at J. Walter Thompson as a regional planing director and was the co-author of AMV's case study on the Government's rear seat-belt safety campaign, which was a four-star winner at the 2000 IPA Effectiveness Awards.
"Vanella's CV speaks for itself,
Herd added. "She has worked at the top of one of the best planning departments in London as well as being very likeable."