The league said Mayo had tested positive for using dehydroepiandrosterone (DHEA), a steroid hormone that is naturally produced by the body in the adrenal glands.
"I'm extremely disappointed that I'm going to miss the next 10 games, particularly as our club is making a push for the playoffs," Mayo said in a statement. "I had no idea that the over-the-counter supplement that I took was a substance banned by the NBA. It was an honest mistake, but I take full responsibility for my actions.
"I apologize to my fans, teammates and the Grizzlies organization for regrettably not doing the necessary research about what supplements I can put in my body."
Mayo's suspension will begin Friday when Memphis plays in Philadelphia. He will be eligible to return Feb. 15, when the Grizzlies host the 76ers.
"O.J. had a lack of judgment but has shown complete accountability," team owner Michael Heisley said. "We will continue to support O.J. during this time as we have from the moment he joined the team in 2008. He has unselfishly done everything we have asked of him, and we expect him to grow as a player and a person from this experience."
Mayo played in all 82 games during his first and second seasons with Memphis and had averaged 12.2 points a contest during his 45 appearances in the current campaign.