Brown agreed to terms last month with the Bucs on a one-year deal worth up to $6.25 million with $3.1 million guaranteed and a $2 million signing bonus, but he had yet to sign his contract because he needed to pass his physical.
Brown underwent a surgical procedure last week to repair a torn meniscus.
Coach Bruce Arians said he was excited to have Brown back in the building.
"He had his procedure done, and he looks good," Arians said Tuesday. "I saw him in the training room this morning. All that's done, and he'll be ready to roll."
When Brown will be ready to roll is still not clear, with Arians saying it's up to the team's medical staff to make that call.
"That's strictly up to the doctors, when they give him the green light," Arians said. "One thing you never have to worry about is Antonio being in shape. If anything, he'll be out there too soon -- we'll have to watch him. And the veteran guys, we'll see them all in two weeks."
Brown, along with the majority of the Bucs' veterans, did not take part in Tuesday morning's OTA practice, as Arians told starters they weren't going to be on the field practicing because younger players needed the reps.
Brown led the Bucs in receiving targets over the final four games of the regular season and had a 36-yard touchdown catch in Tampa Bay's wild-card-round victory over the Washington Football Team. He suffered a knee injury the next week against the New Orleans Saints in the NFC divisional playoffs, forcing him to miss the NFC Championship Game.
But Brown returned to play in Super Bowl LV, in which he caught five passes for 22 yards and a 1-yard touchdown.