The Royals have mutually terminated the 36-year-old's contract, 12 months before it was due to expire, as they look to rebuild under Paul Clement.
Former Charlton Athletic and Bournemouth striker Kermorgant's future at the Madejski Stadium looked bleak when overlooked for selection in his side's last two pre-season friendlies.
Speaking to the club's official website, the Frenchman said: "During my time at Reading, I have experienced both the highs and lows of football - the excitement of a third-placed finish and a playoff final at Wembley, then the frustration of injury and the disappointment we all felt as a group last season.
"I would like to take this opportunity to say 'thank you' to everyone at the club. And, of course, I would also like to wish the players, all the staff and the fans the very best of luck ahead of the brand new Championship season and for the future."
Chief executive Ron Gourlay hopes to keep Kermorgant, who was originally due to retire this summer, involved with Reading in some capacity.