Wilson completed 185 yards worth of passes in a starting role, completing 13-of-19 throws and running for 58 yards.
Matt Flynn, signed as a free agent, was rested due to a sore elbow and watched as Wilson tried to grab the job away from him.
Seattle's first three possessions ended with field goals from Steven Hauschka and Wilson then threw second-period touchdown passes of 21 yards to Kellen Winslow and 11 yards to Charly Martin.
Another Seattle rookie, Robert Turbin, ran 14 times for 93 yards and scored on a 25-yard romp in the third period. The Seahawks have won all three of their exhibition games.
Seattle added to the rout on a 75-yard interception return for a score by Earl Thomas and a 92-yard return of a punt by Golden Tate.
Kansas City's Matt Cassel completed 19-of-34 passes for 168 yards and a touchdown. The Chiefs fell to 1-2.