Poyet's men host Palace on Saturday in a match that could have crucial implications in the fight for Premier League survival.
The Stadium of Light club, who sit 19th in the table, head into the fixture on the back of a League Cup final defeat to Manchester and an FA Cup quarter-final loss at Hull City.
Brown and Gardner both missed the reverse at the KC Stadium with knocks, but they are in contention to return to the team after shaking off their respective problems.
That leaves goalkeeper Keiren Westwood as Sunderland's only absentee as they look to pull out of the bottom three with victory over Tony Pulis' side, who are currently three points above the Wearsiders in 16th.
"Team-wise everybody is fit, which is amazing," Poyet told the club's official website.
"Craig Gardner is back in full training with us, and Wes (Brown) has trained for the last three days."
