Overbay had four of New York's 16 hits. He produced a two-run homer during a four-run second, added an RBI double in the fourth, contributed another run-scoring double during a five-run sixth and brought home the game's final run with a single in the ninth.
The Yankees won their third in a row and gave Manager Joe Girardi his 500th victory.
New York's offensive surge made a winner out of Phil Hughes (2-2) even though he gave up six runs in 5 2/3 innings. The Yankees had scored 10 times before Hughes left the game.
Rookie Wade Davis (2-3) was roughed up for seven runs on seven hits in five innings to take the loss. Kansas City has dropped four of five.