"To Eagles fans everywhere, I want to thank you for the way you supported me every single day. I could feel it. You made my time here special," Sproles said in a letter posted to the Eagles website.
The letter is titled "Eagles fans, I gave you all I had."
In November, Sproles was ruled out for the remainder of the season due to a torn right hip flexor muscle.
Sproles originally suffered a partial tear of the muscle during the game against the New York Jets on October 6.
Sproles went through four weeks of rehabilitation including a return to practice on October 30.
He was fully cleared after "extensive testing and participation in practice," the Eagles said.
The team said Sproles played in the November 3 game against the Chicago Bears without reporting any issues.
He returned to the team on November 11, but reported the injury a few days later.
According to the team, further testing revealed the torn hip flexor muscle.
Statement from the Philadelphia Eagles regarding RB Darren Sproles pic.twitter.com/SomTcRI0g3— Philadelphia Eagles (@Eagles) November 15, 2019
Sproles is a 15-year veteran and three-time Pro Bowler. He was selected 130th overall in the fourth round of the 2005 NFL draft by the San Diego Chargers. He was acquired by the Eagles in 2014.
"My favorite memory from my career is the Parade of Champions down Broad Street. Seeing how this entire city, and it sure looked like the entire city was there, came together to rally behind this team is something that inspires you to want to go out and bring it home each and every year," Sproles wrote in his letter.
Sproles, 36, said he was motivated to return for his 15th NFL season in part so he could finish his career fifth in all-purpose yards.
He also returned to honor an agreement. His daughter made a bet with him: If she qualified for the Junior Olympics, he had to play one more year. She qualified, and Sproles obliged.
Sproles, 36, moved into fifth place in career all-purpose yards, reaching the mark on a punt return in the third quarter of that October game against the Jets.
He limped off the field a few plays after the punt return and did not return.
ESPN contributed to this report.