Garrard missed last week's contest after suffering an Oct. 18 concussion. But he didn't miss a beat against the hapless Cowboys, completing his first 12 throws en route to a 17-for-21 passing display for the Jaguars (4-4).
Mike Sims-Walker grabbed eight of Garrard's passes for a career-high 153 yards and two touchdowns and Marcedes Lewis contributed a pair of scoring receptions in the victory.
Maurice Jones-Drew ran the ball 27 times for 135 yards and Derek Cox became the first Jaguar to intercept two passes in a game since 2006. In all, Jacksonville intercepted the Cowboys four times.
Dallas signal-caller Jon Kitna, subbing for the injured Tony Romo, completed 34-of-49 passes for 379 yards and a touchdown for the Cowboys (1-6).
Dallas lost a fourth straight game for the first time since the last four weeks of the 2002 season.