Sitton, 32, made the announcement Thursday during a radio interview on ESPN Madison and ESPN Milwaukee's Wilde and Tausch. The 6-foot-3, 318-pound offensive lineman made the decision public just hours after the birth of his child.
"My wife just gave birth to our baby boy at 4 o'clock this morning, and I am retiring from the NFL," Sitton said.
The central Florida product was a fourth round pick in the 2008 NFL Draft. He played his first eight seasons for the Packers, before joining the Chicago Bears in 2016. Sitton signed a two-year, $18 million contract with the Miami Dolphins in March of 2018, before landing on injured reserve in September due to a torn rotator cuff he sustained in Week 1.
Miami released Sitton on March 13 with a failed physical designation. The four-time Pro Bowl selection started all 16 games for the Packers in six of his eight seasons with the franchise, including every game from 2012 through 2015.
He started 13 games for the Bears in 2017 before appearing in just one game for Miami in 2018. Sitton won a Super Bowl in 2011 with the Packers.