He will follow the same path as his former Pirates team mate, Rob Cook, who made the move to Gloucester almost 12 months ago.
Upon his arrival at the Pirates, Bentley quickly established himself as a skilful, ball playing fly half and his signing will add strength in depth at a crucial position says Director of Rugby Nigel Davies.
"We're delighted to add Jonny to the squad and look forward to him reporting for preseason training next week.
"Fly half, it goes without saying is a pivotal position in any team. It's very likely that we'll lose Freddie Burns to international duty at times next season, and Tim Taylor is still working his way back to fitness after knee surgery.
"So, I felt it was important to add another specialist 10 to the squad and Jonny's a very polished performer. I know he can't wait to get up here and show what he can do, and I think he's going to be a valuable contributor for us."
Bentley himself told the club website that the move to Kingsholm has happened quickly, and thanked the Pirates for allowing it to happen:
"It all came a bit out of the blue to be honest. My agent told me that Gloucester had been in touch and it all went from there.
"I can't thank the Pirates enough for the way they've gone about it. They've stuck by me over the past couple of seasons when I've had some injury problems. They've been really good to me.
"I spoke to Josh Lewsey about it, and he said that they weren't the sort of club to stand in anyone's way and that they would wish me all the best.
Bentley will link up, of course, with his former team mate at the Mennaye, Rob Cook, and revealed that the pair have been in regular contact.
"Cookie is a good mate and we talk all the time. His move to Gloucester has worked out brilliantly and he can't speak highly enough of the club.
"I've actually been up to watch a couple of games - against Fiji and Exeter last season - and the atmosphere at Kingsholm was amazing.
"I can't wait now to get up there and meet the boys and get stuck in. The prospect of playing in the Aviva Premiership and Heineken Cup is genuinely exciting, I'm really looking forward to it."