He shared it Tuesday on Instagram, saying he "hated to hear" the news because Gettleman was one of the only people who "constantly checked on my well being, condition and state of mind in the time that I've been suffering from my injury."
Oher has been in the concussion protocol since September. Although a league source recently told ESPN that Oher will report to training camp on July 25, his future with the team remains uncertain.
That Oher heard the news of Gettleman's firing while on the way to see Dr. Micky Collins, a concussion specialist in Pittsburgh, suggests he's still dealing with the concussion.
Panthers coach Ron Rivera reacted Tuesday to the news as well, telling The Charlotte Observer in a phone interview that he was "surprised" by Gettleman's firing but still believed the Panthers would be a playoff contender this year.
"The decision was made, and that's what we're going to do," Rivera said. "The biggest thing is Dave did a great job for us. He helped me to grow as a coach, he helped to put the final pieces of the puzzle together and he helped us get to the Super Bowl."
Oher's support of Gettleman shouldn't come as a huge surprise. Gettleman flew to Nashville, Tennessee, on May 5 to visit Oher, who was also facing misdemeanor charges for allegedly assaulting an Uber driver.
Gettleman told the team website that "we really had a great visit."
"We talked for an hour, had lunch, it was a very comfortable conversation," Gettleman said. "We talked about a lot of things -- nothing about football. It was about him, how he was doing and the issues he was dealing with. It started and ended well. And after we met, Michael did follow up for a few days. However, the communication has stopped.
"Our No. 1 priority is a healthy Michael Oher. This is not about football, this is about Michael."
Oher's support of Gettleman came after a few former Panthers -- wide receiver Steve Smith, running back DeAngelo Williams and cornerback Josh Norman -- expressed pleasure on social media that Gettleman had been fired.
Williams, who was released after the 2014 season, referred to Gettleman as a "snake" on Twitter.
Smith, released after the 2013 season, tweeted, "It's Okay! Dave I know how you feel."
Carolina outside linebacker Thomas Davis also spoke out on Tuesday, telling a Charlotte television station that it was unfair to blame the firing on possible contract disputes between Gettleman and veteran players.
Davis and tight end Greg Olsen both are seeking extensions. Davis, 34, is in the final year of his deal. Olsen, 32, has two years left.
Multiple sources told ESPN that concern over Gettleman's handling of past negotiations, along with a concern that Davis and Olsen could be disgruntled going into training camp, played a part in the decision by owner Jerry Richardson to fire the GM.
"We had actually engaged in contract talks," Davis told NBC Charlotte. "They presented something and we presented something back, and we were just in the process of negotiating.
"I felt like the talks were going well. There's nothing that's going to happen overnight. It's a negotiation for a reason."
Davis said it's "really sad and disappointing when you hear all the people that are saying that the reason Mr. Gettleman was released was because of me or Greg."
"That's an unfair statement. I think that's something that you guys are giving us too much credit; we're not that important in the grand scheme of things and [ultimately], Mr. Richardson made a decision and it's something that we're all going to live with."