Terms of the deal were not immediately available.
Oher, 28, was recently released by the Tennessee Titans after starting 11 games this past season. He played his previous five seasons with the Baltimore Ravens after being selected in the first round (23 overall) of the 2009 draft.
Oher, 6-foot-4 and 315 pounds, was the focus of the "The Blind Side," a 2009 movie tracking his rise from an impoverished background to adoption to a star football player.
The Memphis native is a former high school and college (Ole Miss) teammate of Carolina defensive end Greg Hardy, who is not expected to be re-signed once he becomes an unrestricted free agent Tuesday.
"We look forward to having Michael be a part of what we are building here," coach Ron Rivera said in a statement. "He's a pro who understands what it takes to win. A big part of why we pursued Michael was his relationship with offensive line coach John Matsko and the opportunity to have him work with Ray Brown. We are excited to have him."
Oher visited the Panthers prior to the NFL combine in Indianapolis two weeks ago. He spent his first two seasons at Baltimore working under Matsko, then the Ravens' offensive line coach.
"He's a great coach," Oher said, according to the Panthers' official website. "I learned a lot from him my first two years when he was in Baltimore, and the assistant that was with him in Baltimore carried his techniques on for a couple of more years. I'm excited to be back with him, working with him again. He knows how to teach football."
A toe injury forced the Titans to place Oher on injured reserve after he started the first 11 games at right tackle. He then had surgery to address the toe issue.
"I'm great now, back doing everything full speed," Oher told Panthers.com. "It was something that had bothered me every year in the NFL. While lining up in my stance, sometimes I would feel it. It was something I had needed to get taken care of. I finally got it done and I can see the results from it already."
Oher started 16 games at left tackle in 2010 and started 80 regular-season games overall for the Ravens, including 16 in 2012 when they won the Super Bowl.
The Panthers began looking for a left tackle after deciding not to re-sign Byron Bell, their starter last season. They still may consider drafting a tackle with the 25th pick of the draft.