The promotion will run in the David Prever and Chris Best breakfast shows.
Beginning this week, Prever and Best will tell listeners each morning they are having breakfast with a celebrity in a Marriott Hotel in a certain city and listeners will then have to guess the identity of the celebrity.
Each day listeners will win a weekend break for two to a Marriott Hotel in the UK, Europe or the Middle East.
There will also be an opportunity to win a weekend away by visiting Smoothfm.com.
The promotion is designed to highlight Marriott's summer Stay for Breakfast offer.
Roy Bennett, Smooth fm's managing director, said: "Both stations provide a perfect platform for the hotel chain to reach its target market."