The comedian quit his long-running ITV1 series TV Burp back in September after rejecting a £1m pay rise which would have seen his salary top £4m.
He is now said to be in talks with Channel 4 boss Jay Hunt about a movie and a sketch show and hopes to sign a £2m deal when his golden handcuffs contract with ITV ends in April.
"Harry has lots of ideas and fancies doing something different for a while, especially his own film. That doesn't really fit in with ITV's plans for him so he is interested in doing a deal with Channel 4," a source told The Mirror.
"They have offered him big budgets and a lot of creative freedom to make what he wants, and that's what attracts him to the offer more than the pay cheque.
"He has been earning millions with ITV for years so it is not all about the money. For Harry it's all about doing projects he loves so it seems almost certain he'll head to Channel 4. And all his fans would love to see a Harry Hill movie."
The film could be released in cinemas and on DVD as well as being shown on Channel 4. A new Harry Hill television series is likely to launch around the channel's 30th anniversary in November.
Hill originally rose to prominence on Channel 4 with The Harry Hill Show, which ran for three series from 1997 before he moved to ITV.
Hill's move back to Channel 4 is said to have been prompted by creative differences with agent Jon Thoday, managing director of TV Burp producer Avalon. He was at the centre of a bidding war between Sky and the BBC after splitting from Thoday last year.