The British soul star and the Forget You singer struck up a friendship while she was holidaying in St Lucia.
According to the Daily Star, he insisted they put their heads together for a collaboration before she returned to the UK.
A source told the newspaper: 'Her voice is as good as ever. She might look frail when you see her but don't be deceived, the voice is still there. Amy has a house in St Lucia and decided to fly out. She and Cee-Lo just clicked and he said he wouldn't leave the island until the track was done. Amy's album is entirely finished, so it's just a case of the record company deciding when to release it.'