Giovani dos Santos earned his first MLS start and paired next to Robbie Keane once again, with Gyasi Zardes shifting to the right wing to accommodate the Mexican international.
With just 51 seconds on the clock, Seattle briefly spoiled the party when former Galaxy player Chad Barrett did well to re-direct a beautiful Erik Freiburg cross into the net.
It didn't take long for the Galaxy to equalize, however. In the 12th minute, Juninho lofted a cross into the area, and Gyasi Zardes was unmarked at the near post to poke the ball home with the outside of his right boot past a sprawling Stefan Frei.
After the goal the Galaxy pressed for a second, probing outside the Sounders area but unable to find space near the Seattle goal.
The Sounders had chances of their own. In the 24th minute, Chad Marshall had a free header inside the box, but his attempt was deflected. A few minutes later, Zach Scott put a header into the back of the net, but was ruled to be offsides on the play.
Giovani Dos Santos' first real opportunity came late in the half when he pulled a shot outside the box late in the half. Not soon afterwards, Steven Gerrard fed a clever backheel to Robbie Keane, who's blast didn't miss by much.
As has been the case with LA recently, the floodgates opened in the second half. In the 47th minute, AJ DeLaGarza crossed a low hard ball inside the area that dos Santos corralled to Robbie Keane, and Keane made no mistake finishing from close range.
The Galaxy dodged a bullet when Omar erroneously turned the ball over inside the box to a wide-open Oniel Fisher, but the subsitute could only manage a low weak shot that Ricketts saved easily.
In the 64th minute, Galaxy nabbed a third when Robbie Keane slotted dos Santos racing down the center of the pitch, and Dos Santos made no mistake lifting a shot over Stefan Frei into the net for Giovani to open his MLS account.
A few minutes later, Alan Gordon made way for dos Santos as he jogged off the field to a raucous ovation.
The Galaxy committed another defensive error in the 70th minute when Donovan Ricketts spilled a routine cross, but Robbie Rogers was quick off his feet to clear the ball off the line.
On the other end of the field, Sebastian Lletget danced inside the box and squared a ball that rolled to Alan Gordon, but his point-blank shot rang off the post.
Gyasi Zardes was unlucky to score when he accepted a inch-perfect pass from Steven Gerrard and dribbled in alone on goal, but Stefan Frei was able to make an impressive stop.
Alan Gordon almost pulled off a spectacular finish when he headed the ball high in the area before attempting an audacious bicycle kick that bounced just wide of Frei's goal.
With the win, the LA Galaxy continue to build momentum while Seattle has now lost five straight games. LA battle FC Dallas on the road next Sunday.