The Green Bay Packers finished first in the NFC North with a 10-6 record in 2003. On January 4, 2004, Barnett started in his first career playoff game and made six combined tackles (three solo) during a 33-27 overtime victory against the Seattle Seahawks during the NFC Wildcard Game. The following week, he made five solo tackles and defended two passes as the Packers lost 20-17 at the Philadelphia Eagles during the NFC Divisional Round and were eliminated from the playoffs.