Former Cleveland Browns center JC Tretter on Thursday announced his retirement after nine years in the NFL. 

Tretter, 31, released a statement on social media saying he was making good on the promise he made to himself in college to retire "on my own terms," adding that he plans to continue on in his role as president of the NFL Players Association.

"I am proud of what I’ve accomplished and how far I’ve come from that night when I made the pledge to myself. I feel like if my 31-year-old self could talk to my 20-year-old self, I could earnestly tell him that we did it. We did everything we said we’d do and more," he wrote, in part.

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"My time on the field may be over, but I’m not stepping away from football. I'm looking forward to doubling down on my work as NFLPA President and pushing for more progress on behalf of the great players of our game, past, present, and future." 

Tretter was drafted by the Green Bay Packers in the fourth round of the 2013 NFL Draft, where he played for three seasons before signing with Browns in 2017. He signed a contract extension in 2019 but was released in March. 

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Tretter was instrumental in setting up team COVID-19 protocols and helping the league navigate pandemic-related challenges during the 2020 season.

In an interview with Sports Illustrated published Thursday morning, Tretter spoke about his ongoing knee issues last season and seemingly suggested that it wasn’t the status of his injury that would keep him sidelined. 

"Guys would be like, ‘Oh, like how are your knees doing?’" Tretter recalled in his interview with the outlet. "And I always said, ‘My NFLPA job is gonna end my career well before my knees end my career.’"

After becoming a free agent, Tretter said no teams he was potentially interested in playing for expressed the desire to add him to their roster, despite a salary request "well below the value I bring." 

While his career on the field may be over, Tretter remains positive about continuing on in his role as NFLPA president. 

"I would argue I'm going to accomplish more in the next 18 months than I would have ever gotten close to playing football during that time," he said. 

"I’m very excited about what’s next."

The Associated Press contributed to this report.