The 700-strong chain, which is owned by Somerfield, is planning to relaunch in the spring, overhauling its stores in a bid to entice consumers back.
It has already launched a range of slickly packaged economy products, called Simply, in response to research showing consumers were embarrassed to buy supermarkets' own-label economy products.
McCann-Erickson has handled the brand's advertising until now, as well as that of its sister brand Somerfield. Universal McCann will continue to handle media buying, while MCBD will handle media planning.
Recent creative work for Kwik-Save showed a millionaire family that shopped at Kwik-Save. MCBD is working on above-the-line activity, set to break in May.
Kwik-Save was bought by Somerfield in 1999 and, at the time of the takeover, was due to be phased out and rebranded to Somerfield. This strategy was abandoned in favour of promoting Kwik-Save separately, with the focus on the chain's prices, in 2001. This led to the then group brands director, Nick Adderley, leaving the company.
Gill McComas, Kwik-Save's marketing director, said: "We decided to review our account to help us with our pace of change. MCBD has offered us strategic and creative insights we believe will significantly help our brand. We were impressed with its strategic in-put and its creative and media recommendations."
MCBD's chairman, Jeremy Miles, added: "It's wonderful to get involved with a business which is undergoing fundamental change. It has also been a great pleasure to be invited to look at and contribute to their business from top to bottom."