The 25-year-old spent his formative years with the North East club before joining Celtic for a £2.5million fee last summer.
"I'd like to go back to Newcastle at some point, if the opportunity arises," said Forster, who was speaking to BBC's Late Kick-Off. "I'm a Newcastle fan and I've got unfinished business there.
"It was a wrench to leave, it's my hometown club. But it wasn't meant to be. I enjoyed my time out on loan and after enjoying playing week in week out it was important I carried on playing. I wanted to be No 1 and it was clear that wasn't going to happen at Newcastle.
"Everyone wants to be playing in the Premier League. It's the place to be.
"At the minute I'm very happy at Celtic and playing Champions League Football, but long-term it would be nice to play in the Premier League."