Mike Magee bagged a hat-trick and skipper Robbie Keane added a fourth as Bruce Arena's Galaxy dominated proceedings at The Home Depot Center to begin the new campaign with a commanding result.
Magee volleyed home from 12 yards in the 38th minute to open the scoring before receiving a neat through ball from Keane to curl over Fire keeper Sean Johnson with just over 20 minutes remaining. He then produced his first-ever treble when he controlled a deflected ball with his chest before turning and volleying into the roof of the net on the turn.
Keane scored with a classy side-volley ten minutes from time to wrap up the contest in front of just over 20,000 fans on a perfect day in California.
The Galaxy will now prepare for their CONCACAF Champions League quarter-final first leg with Costa Rican club Herediano on Thursday prior to the return bout in Carson on March 14.