O’Neill opened the scoring with his first goal of the season in the fifth minute when he headed home a cross from Kelyn Rowe.
Benezet scored his second goal of the year and doubled the Sounders’ advantage in the 14th minute after he took a pass from Will Bruin and fired past Thomas Hasal from close range.
Brian White scored his team-leading 10th goal of the year in the first minute of first-half stoppage time and halved the Whitecaps’ deficit to send the teams into the locker rooms with the Sounders ahead 2-1.
Bruin scored his third goal of the year in the 55th minute to provide insurance when he beat Hasal near post after a great interchange in the box.
Summer signing Chú entered as a second-half sub and scored his first club goal in the 90th minute to seal the win with a clever finish to the far post.
The Sounders extended their Western Conference lead to five points over Sporting Kansas City before a road clash at the Houston Dynamo next Saturday (5:30 p.m. PT; FOX 13+, Prime Video, El Rey 1360AM).
Playoff streak continues
The Sounders booked their 13th consecutive trip to the postseason, extending their MLS record. Seattle has reached the MLS Cup Playoffs every year since their MLS inception in 2009.
Another early start
For the second straight match, the Sounders scored at home inside five minutes. Cristian Roldan scored in the second minute in a 3-0 win over the Rapids last week before O’Neill found the back of the net inside five minutes on Saturday to give the Sounders all three points.
Starting up top for Raúl Ruidíaz, Bruin had his second straight massive game up front, scoring once and setting up another. The 31-year-old has been indispensable in Head Coach Brian Schmetzer’s attacking schemes this season and is continuing to prove his bona fides as a No. 9 in the Sounders’ system.