On October 17, 2004, Winfield recorded seven combined tackles, deflected a pass, and made his first interception as a member of the Vikings during a 38–31 win at the New Orleans Saints. Winfield intercepted a pass by Saints’ quarterback Aaron Brooks, that was intended for wide receiver Ernie Conwell, and returned it for a 56-yard gain during the first quarter. The following week, Winfield made eight solo tackles, two pass deflections, and intercepted a pass attempt by Titans’ quarterback Billy Volek during a 20–3 victory against the Tennessee Titans in Week 7. In Week 9, he collected a season-high 13 combined tackles (ten solo) and broke up two passes during a 31–28 loss at the Indianapolis Colts. Winfield was inactive for two games (Weeks 14–15) due to an ankle injury. Winfield finished the 2004 NFL season with 85 combined tackles (70 solo), five passes defenses, three interceptions, and two forced fumbles in 14 games and 14 starts.