The eccentric playboy is taking in the city, which he describes as "windy, wet and cold" as he makes a record of his bid to become an international entrepreneur. "Like Richard Branson, like the pickle", he told UTV.
Keith took time out from his busy filming schedule to explain more about the movie, which he said he wants to be seen as "the stupidest film of the year".
"The film is a real rags to riches story and then I go back to rags because I realise life isn't about being rich and famous, it's about your friends and family and who you surround yourself with," he said. "It's quite moralistic."
The Celebrity Juice host has built up a fan base in the city and he said he is mostly enjoying meeting locals.
Belfast has some lovely buildings and some lovely people. There are also some people who want to tell you you're rubbish and then get their photograph taken with you.
Keith Lemon
"It's an endearing slagging off," he said.
Keith Lemon: The Film also stars Kelly Brook and Verne Troyer, who have been spotted hanging out in Belfast.
Former Page Three girl Kelly is often listed among the UK's most beautiful people, but Keith said he is not convinced by her.
"I'd almost go so far as to say Kelly is hideously deformed. Then the makeup lady puts her face on and she's Kelly Brook.
"Verne is like my little brother, who's 15 weeks old. He's a lovely fella, beautiful manners," he added.
While Keith claims "92% of the film is made up, the rest is based on true life experiences" but would not reveal which parts are representative of his real life, director Paul Angunawela said his star is a great actor.
"Keith does bring out the best in the actors. It's quite a big film, with a heart and people are here because they want to work with Keith."
Paul explained that the intimate setting was ideal for his movie.
"Everything is within walking distance, which is great and the people of Belfast is what we like, they're very enthusiastic."
Filming has already taken place at the Drawing Rooms, the Waterfront Hall and many streets across the city. Paul said there are many great locations throughout Belfast.
"People really want to help out and it's a very different atmosphere to London. We will have shot most of Belfast by the time the film is cut," he added.
