"Today I am announcing my retirement from the game I love," Johnson wrote on his post. "I lived a dream which few can say but it's time to move on. I want to thank the Chargers organization for giving me a home these past three years.
"I have nothing but respect for the players, coaches, front office staff and fans that were apart of me and my families lives. It's been a great ride!! I also want to thank my Baltimore family. Where I leaned to be a pro and conduct yourself like a warrior on the field. Where I spent 9 of the best years of my life."
Johnson, 33, is best known for his long run with the Baltimore Ravens, where he started 95 games at multiple linebacker positions. He spent his final three seasons with the Chargers, where he became one of the biggest leaders in the locker room. In January, teammates voted Johnson the co-Most Inspirational Player of the Year. He was recognized with the same award in 2013.
"He's a guy who could probably be in the training room a lot, probably could take some days off a lot because he's banged up and sore. But it's, 'Hey, Jarret. How are you doing?' 'I'm good.' You know it's not true. He's such a warrior. I think it's impressive and a compliment to him that enough guys voted him and wrote (his name) down. He's a linebacker; he mainly plays on base downs. For him to have that impact on the team says a lot about him."
Johnson was due $5 million in base salary in 2015 and was a release candidate for San Diego. Instead, Johnson walks into the sunset.