The Omnicom agencies take over from Element 79 in Chicago, which has handled the business for the past six years. PepsiCo spent more than $200 million on both brands in measured media last year, according to Nielsen Monitor-Plus.
PepsiCo said: "We believe Gatorade and Tropicana could benefit from a partnership change."
Element 79 was established in 2001 to handle PepsiCo business that left FCB after IPG bought its True North parent. Coca-Cola is an IPG client.