
The agency won the business following a pitch against Rainey Kelly Campbell Roalfe/Y&R, The Red Brick Road and Dye Holloway Murray.
The Union, the Edinburgh-based agency that was the incumbent on the account, did not repitch.
JWT's first campaign for Baxters will be to promote its soup range, and is expected to break later this year.
The agency will be responsible for working on the brand's entire range of products, which also includes preserves, condiments and chutneys.
The appointment does not affect MediaCom Scotland, which will continue to handle the brand's media business.
David Milner, group commercial director for Baxters, said: "We are excited and confident about the strategy and the idea JWT has delivered, and excited about working together."