Gordon - playing in the absence of injured captain Robbie Keane (groin) - netted the only goal of the match in the 23rd minute.
Juninho whipped in a free-kick and Omar Gonzalez's header across the face of goal found unmarked 33-year-old Gordon, who nodded home at the back post.
Gordon's header ended two matches without a goal for MLS Cup champions the Galaxy, who snapped a run of back-to-back defeats following shutout losses to Vancouver Whitecaps and DC United.
The Sounders, who were without Clint Dempsey due to a hamstring injury, had opportunities to level the match but they could not find a way past Galaxy goalkeeper Jaime Penedo.
Los Angeles are sixth in the West with eight points from six matches, a point clear of eighth-placed Seattle, who have a game in hand.
Orlando City returned to winning ways in Portland thanks to Cyle Larin and Kaka.
Larin and Kaka were both on target as Orlando City accounted for Portland Timbers 2-0 at Providence Park.
Orlando City hit the front via Larin - the number one pick in January's SuperDraft - who chested Kevin Molino's cross into the net for his first MLS goal after 30 minutes.
The visitors sealed the points five minutes from time, when Brazil international Kaka converted a penalty at the second time of asking following a foul on substitute Carlos Rivas by Timbers keeper Adam Larsen Kwarasey.
Kaka's initial spot-kick was saved but the former Real Madrid midfielder was awarded another attempt due to encroachment in the box.
Orlando City, who ended a three-match winless run, climbed up to third in the Eastern Conference, level on eight points with New York Red Bulls and New England.
Portland are bottom in the West on goal difference.
