The home side opened the scoring in the 17th minute when Bruin drew Sounders 'keeper Michael Gspurning off his line before laying the ball off for Barnes to hammer it into the unguarded net.
Barnes doubled Houston's advantage four minutes later with a thunderous strike from 30 yards out, firing a laser into the upper corner that left Gspurning with no chance.
Seattle pulled one back in the 65th minute when Marc Burch's free kick was headed home by Shalrie Joseph, but Houston restored its two-goal lead nine minutes later when Brad Davis nodded a loose ball to Bruin in the box, allowing the Dynamo striker finish from close range with an agile effort.
The win sees Houston (10-7-6) improve to 36 points on the season to maintain a three-point gap over the New England Revolution.
Seattle (10-8-4) sees its four-game unbeaten run come to an end as the club stays put on 34 points for the season.
08/17 23:01:02 ET