Dillon Powers, Drew Moor and Gabriel Torres also scored for Colorado, which went ahead 14 seconds in and never looked back.
Deshorn Brown opened the scoring 14 seconds in, setting the stage for a dominating first-half that also included goals from Dillon Powers and Drew Moor, as well as a second strike from Brown. Gabriel Torres then notched the Rapids' fifth in second-half stoppage time.
Colorado, which has only lost two games since June 29, moved into fourth place in the Western Conference — just four points behind first-place Real Salt Lake. Seattle sits in second, one point back of RSL but with two games in hand.
Brown scored the second-fastest goal in MLS history when Torres slipped him in behind the Seattle back line and the Jamaican slotted a shot past Michael Gspurning.
The Rapids doubled the advantage in the 10th minute when Powers nodded home a quick corner kick from Vicente Sanchez. And Colorado made it 3-0 in the 31st minute when Brown overpowered Seattle right back DeAndre Yedlin before tucking away his shot.
The home side capped the opening period with another tally four minutes before halftime as Hendry Thomas' header deflected in off Moor. Although Eddie Johnson connected with Marc Burch's long ball and beat Clint Irwin with a 63rd-minute strike, the Sounders would get no closer.
To make matters worse, Seattle saw defender Zach Scott sent off late with a second yellow card in his second straight match played. Colorado then restored the four-goal margin in the match's dying stages when Torres put his shot inside the far post.