Wimpey's media briefs were allocated by region and shared between the Surrey-based agency and Universal McCann Manchester, which pitched for the work alongside a third agency, Think BDW.
Space and Time Media chairman Peter Jones said: "This is a fantastic win for the business and one of which the whole team can feel justly proud."
Karen Cullis, George Wimpey's group marketing manager, said the agency's geographical diversity, integrated approach and insight into the new home industry proved key to winning the account.