Carlson Marketing Group will work primarily on the £1m Stella Artois business, which was previously handled by Boy Meets Girl S&J.
The Marketing Store will oversee the Castlemaine XXXX business; Vitamin V will handle speciality beers, ales and stouts; and Stand will work on Tennent's.
The roster will handle all the brewer's below-the-line activity except point-of sale, manufacturing, PR and sponsorship.
Interbrew previously used 10 agencies across its beer business. Creative agencies Bartle Bogle Hegarty and Lowe are unaffected.