Details of what Peterson did, and when he did it, remain confidential, as per the NFL's PED policy. But he dropped his appeal, a source told ESPN's Adam Schefter.
Peterson held a charity event Thursday night and said in a statement that he was sorry, but he thinks people understand his character and his commitment on and off the field to his teammates and the Cardinals organization.
"That's why this is very very hard for me, because, obviously, I've never been in this situation before and never wanted to have my name attached to anything like this," Peterson said. "But I'm looking to move forward and put this behind me."
"Patrick recognizes how disappointing this is for everyone in the organization as well as our fans," the Cardinals said in a statement. "As we all do, he understands that regardless of intent he is ultimately responsible for everything he puts in his body. Our coaching staff and our players are now aware that we will have to play the first six games without Patrick and they understand they have to rise to the challenge that it presents."
Peterson, who is eligible to participate in all offseason and preseason practices and games, will miss Arizona's regular-season opener vs. the Lions, then games at Baltimore, at home against the Panthers and Seahawks, at Cincinnati and at home against the Falcons.
He will be eligible to return Oct. 20 at the New York Giants.
Peterson has started all 128 games since being drafted by the Cardinals in 2011, and his 23 interceptions are tied for third-most in the NFL.
He is the 13th player to make the Pro Bowl in each of his first eight NFL seasons, but that streak will come to an end. The league's performance-enhancing drug policy states that any player suspended for a violation "will be ineligible for selection to the Pro Bowl, or to receive any other honors or awards from the League or the Players Association."
Earlier this month, on The Adam Schefter Podcast, Bengals wide receiver A.J. Green called Peterson the best cornerback in the league.
The three-time All-Pro did not report to the Cardinals' voluntarily minicamp last month because he was upset with the team. There has been trade speculation regarding Peterson, but now he is not scheduled to be reinstated until shortly before the NFL's trade deadline.
At his pre-draft news conference last month, Cardinals coach Kliff Kingsbury said he was not concerned about Peterson's absence from this spring's camp.
"It's voluntary," Kingsbury said last month. "I communicated with Patrick. We know where he's at and we know what's going on. Kind of a conversation to keep between ourselves. If he hadn't communicated and we didn't know what was going on, I think that would be a different matter. It is a voluntary camp. We know that Patrick wants to be here and wants to be a part of this team."
Arizona has been aware of Peterson's pending suspension, and the Cardinals used the 33rd overall pick in last month's draft on Washington cornerback Byron Murphy.
Peterson has two years left on his contract and is set to make a base salary of $11 million this season and $12.05 million in 2020. This six-game suspension is set to cost Peterson $3,882,352 in lost wages.