The Interpublic agencies will handle the account through a new partnership called MC Media, which also includes WPP's outdoor media planning and buying agency, Kinetic.
MC Media will be based in Chicago, and will handle media duties for everything except digital and Hispanic work, according to MillerCoors -- the newly-formed venture between Molson Coors Brewing and SABMiller that combines their US operations.
It will be led by Tim Spengler, president of Initiative USA, who will become chairman of MC Media.
MillerCoors plans to name a Hispanic media agency by the end of the year. Its digital media planning and buying, along with creative assignments, will be handled by Publicis Groupe's Digitas and Microsoft Corp's Razorfish.
The review was called in October, almost a year after SABMiller and Molson Coors -- the second and third-largest US brewers respectively in terms of sales and profits -- announced their intention to merge. This move was designed to challenge market leader Anheuser-Busch, the brewer of Budweiser, which is in the process of merging with Belgian brewing giant InBev.
Other agencies involved in the review included Starcom, the incumbent on Miller's media planning and buying, and media agencies Tapestry and Bromley. Initiative previously handled media duties on Coors.
Jackie Woodward, MillerCoors' vice-president of marketing services, said: "MC Media recognised our need for dedicated resources from a diverse and respected group of agencies to come together to bring a unique solution to the table that will help us win with beer drinkers.
"The MillerCoors portfolio is a collection of distinctive beer brands, and they displayed knowledge of the industry and a passion to win that we think will serve us well in this tremendously competitive and ever-changing industry."
Bob Bernstein, who will serve as managing director of MC Media, and was previously executive vice-president, chief media officer at DraftFCB, Chicago, added: "All three partners are enormously proud to have won this important assignment. The extended team that will form our new MC Media unit is committed to ensuring that MillerCoors becomes America's best beer company."