The 33-year-old small forward gave a heartfelt goodbye to hoops in an emotional Instagram post ... saying, "I've had so many ups and downs and thankful for every single one of them."

"My entire life all I wanted to be was an NBA player. I didn't even realize, or think what came with that, I just wanted to compete and play basketball at the highest level. I can proudly say, I did THAT!"

CP added, "It wasn't perfect, but it was a blast and I want to take a moment to thank every single person who helped me reach my dreams."

Parsons was a 2nd round pick in the 2011 NBA Draft ... playing for the Rockets, Mavericks, Grizzlies and Hawks over the course of 9 seasons.

In 2020, CP was driving in his Rolls-Royce when he was hit by an alleged drunk driver ... suffering a brain wound, disc herniation and a torn labrum.

Despite the accident, Parsons was working to get back on the court -- in fact, he told us last November that he was training to return to the game, but said the process was "pretty intense".

"Working out, staying in shape," Parsons said at the time, "but trying to still recover from the car crash last year, so we'll see."

Now, Parsons is ready for life off of the hardwood.

"To all the staff, trainers, doctors, coaches, teammates, agents, and most important the fans who supported me, THANK YOU."

Chandler finished his career averaging 12.7 points, 4.5 rebounds and 2.7 assists per game.