The Patriots announced Brady's arrival on their Twitter page.
"Nice to see Brady's back in Foxboro, joining (Randy) Moss and the rest of his teammates for voluntary workouts," the post read.
Brady originally wasn't expected to show up because he has been in Los Angeles to train, a regimen that includes him taking up boxing.
Brady's decision to work out with his teammates comes one day after Patriots owner Robert Kraft, speaking at the NFL Annual Meeting in Orlando, Fla., said the team was ready to begin working on a contract extension for the three-time Super Bowl winner. Brady, 32, is entering the final year of a six-year, $60 million contract extension that he signed with the Patriots in 2005.