It will also signal a return to the West Country for Lewis, who moved to Gloucester from the Chiefs ahead of the 2007-8 season.
He made his first Gloucester appearance as a replacement in 2007-8, but very much made his breakthrough in 2008-9 and has since gone on to make nearly 90 first team appearances as well as representing England at U20 level.
However, the signing of Jimmy Cowan and the emergence of Dan Robson, have seen starting opportunities hard to come by this season and the 23 year old will be hoping for more game time with the Chiefs.
"It's not been an easy decision. Gloucester is all I've known in terms of first team rugby, and I've so many really good friends here.
"However, talking to Rob Baxter, I think I'll get more playing opportunities at Exeter Chiefs next season. And that's what I need at this stage in my career, to be playing regularly.
"There are no hard feelings, I'll always be grateful to Gloucester for giving me the opportunity. I'll miss a lot about the club, especially playing at Kingsholm in front of a superb set of supporters."
Meanwhile, Director of Rugby Nigel Davies confirmed that Lewis still has a key role to play for Gloucester for the rest of the season.
"I firmly believe that Dave needs to be playing, he's a quality player. But with Jimmy (Cowan) coming here, and the way Dan Robson has been playing, it's been difficult for him to get starts and opportunities.
"Sometimes, when you have a lot of good players in one position, this is what happens. But, he'll have a big part to play for the rest of the season, and it's great to have a quality player like Dave to call upon.
"He'll be looking to finish here on a positive note and, when the time comes, we'll wish him all the best. He's been a great servant, a really good pro on and off the field."