Phillips had missed games earlier in the season after fracturing his left forearm against the Dallas Cowboys.
"He will be out for the season, it is unfortunate. He is a great guy and really a very good football player, one of our leaders. It is very, very unfortunate for us," Bucs head coach Jon Gruden said on Monday.
Tampa Bay (9-5) is tied with Atlanta for second place in the NFC South.
Gruden said that linebacker Derrick Brooks, who is tied with teammate Kevin Carter with the league's active record for consecutive games played -- the pair have appeared in 222 straight games going back 14 years -- is doubtful for the upcoming game against the San Diego Chargers with a rib injury.