"Thank you to everyone who supported me along this journey," Leaf tweeted Sunday. "Ton of gratitude in the Leaf household tonight. Thanks to ESPN for giving a flawed human being a chance to be better today."
The former Washington State star played his first three seasons for the San Diego Chargers, before being cut by the Dallas Cowboys four games into the 2001 season. Leaf never took another regular season snap after that season.
Leaf's personal life took a hit following the short NFL career. He was arrested multiple times on burglary and drug charges. He also struggled with an addiction to pain medication.
"I know what the depression and the hopelessness feels like," Leaf told Fox Sports in 2016. "I know what that feels like because I was right in it. The prison, the negative press, it was just a piece of life I had to get through.
"I was so glad I didn't kill myself."
He will be paired with play-by-play announcer Clay Matvick and call games mostly on ESPN2 and ESPNU. Leaf worked for the Pac-12 Network last season and is also the co-host for a show on SiriusXM's Pac-12 channel.
"Ryan has experienced the highs and lows in the game of football, putting him in a position to relate to a wide range of situations players can find themselves in," ESPN's senior vice president of production Lee Fitting said in a news release.
"He will be able to rely on those experiences -- including an unbelievable college career where he was an All-American and Heisman Trophy finalist -- in his analysis, making him a tremendous asset for our team.''