The 31-year-old has agreed an 18-month deal to link up with Pompey boss Richie Barker at Fratton Park..
"It's great to join Pompey," Chorley told the club website. "This is a fantastic football club and I think the only way is up here.
"I've played against the gaffer's former sides and I've always liked the way they went about things, trying to pass the ball out from the back.
"So I've been interested in playing for one of his teams and when he moved to Pompey that interest grew.
"I've played at Fratton Park before with Wimbledon and Leyton Orient and, as I'm sure many people have said before, it's a magical place when the crowd get going.
"I can promise the fans that I'll do whatever I can to help turn the club's fortunes around so we can start moving up the table.
"I've been around the game for some time and will bring a fair bit of experience to the squad. I've played at Championship and League One level, so feel there is plenty for me to offer.
"I'll run through a brick wall for the side I'm playing for and will always stand up and be counted."
Chorley will not be able to make his debut at Morecambe on Saturday as he sits out the final game of a three-match ban.
- Sports & Recreation