Seau, 40, announced his planned return on his "Sports Jobs with Junior Seau" television program on the Versus Network Tuesday, the day before the team made it official that he is back at least for the rest of the 2009 season.
Seau played 13 seasons with the San Diego Chargers and three with the Miami Dolphins. This will be his fourth year with the Patriots. He retired prior to the 2006 season but, four days later, signed for the first time with New England.
He retired again after the 2007 season but returned for four games in 2008 before calling it quits yet again.
Seau is a 12-time Pro Bowl selection and has amassed 1,899 tackles, 56.5 sacks and 18 interceptions over 261 NFL games.
To make room on the roster for Seau, New England released defensive lineman Terdell Sands.