Miller Bainbridge was the incumbent on the account.
Kitcatt Nohr will work on Toyota's customer acquisition and retention activity through prospect and customer relationship management programmes across all media.
The agency will play an important role in the launch of a number of models that the car-maker plans for 2009, including the Urban Cruiser, the iQ and the new Avensis.
Kitcatt Nohr's appointment comes after it was awarded the DM account for the Toyota-owned Lexus marque last July.
A team will work across both brands, led by the managing partner, Marc Nohr, the client director, Lindsay Watson, the planning director, Richard Madden, and the creative partner, Paul Kitcatt.
"We're thrilled we'll now be working across almost the full range," Nohr said.