Throughout training camp, Watson competed against Daniel Graham to be the starting tight end. Head coach Bill Belichick officially named Watson the starting tight end to begin the regular season in 2004. He made his NFL debut and first start in the Patriots' season-opener against the Indianapolis Colts and caught two passes for 16 yards, but exited in the third quarter of their 27–24 victory. He remained inactive for the Patriots' Week 2 win at the Arizona Cardinals and was placed on injured reserve for the rest of the season due to a knee injury. During his absence, the New England Patriots finished first in the AFC East with a 14–2 record and reached the Super Bowl after defeating the Colts 20–3 in the AFC Divisional Round and the Pittsburgh Steelers 41–27 in the AFC Championship Game. Watson received a Super Bowl ring after the Patriots defeated the Philadelphia Eagles 24–21 in Super Bowl XXXIX.