Brady, who was with New England for 20 seasons, winning six Super Bowls, announced he's moving on in a statement on social media.
"Although my football journey will take place elsewhere, I appreciate everything that we have achieved and am grateful for our incredible TEAM accomplishments."
Brady turns 43 in August. His next move has been a hot topic since the Patriots were eliminated from the playoffs in January. Brady can become an unrestricted free agent on Wednesday.
Brady has won four Super Bowl MVPs in nine Super Bowl appearances. Brady is second all-time in passing yards and passing touchdowns.