Mayo's agent, Sean Kiernan, confirmed his client's decision to retire, according to ESPN's Mike Rodak.
The veteran linebacker was selected to two Pro Bowls and captured a Super Bowl during his tenure with the club.
Mayo was grateful to the Patriots organization, and captioned his post "RETIRING A PATRIOT."
Mayo tore his pectoral twice in the past three seasons and suffered a torn patellar tendon, which ended his 2014 season. The last time Mayo played a complete campaign was in 2012.
For the majority of his career, Mayo was one of the anchors of the Patriots' defense. However, he was supplanted by Jonathan Freeny in the starting lineup, while standout duo Jamie Collins and Dont'a Hightower proved to be invaluable staples of the defense.
If Mayo's indeed retiring, the Patriots will save $7 million in cap space.
He was selected 10th overall in the 2008 NFL Draft out of Tennessee.