Fulton County jail records showed Moore remained in custody Thursday night. No details of the arrest were immediately available.
The Falcons released a statement saying the team was aware of the "situation involving William Moore" and was gathering more information.
Moore, a Pro Bowl alternate in 2012 and a free agent after the season, agreed last month to a five-year, $32 million deal, including $14 million guaranteed, to re-sign with the Falcons.
He finished the season with four interceptions and 105 tackles despite missing four games with a hamstring injury.