The 70-foot yachts were docked in adjoining berths in the harbor. Both suffered extensive damage to the upper decks.
More than 40 firefighters responded to the scene around 8:47 p.m. and were able to douse the fire on both yachts in under 30 minutes, according to the Los Angeles Fire Department.
AIR7 HD caught the aftermath of the charred ships as crews were putting out the last hotspots.
Arson investigators were called to take a closer look at what may have ignited the blaze.
LAFD says no other boats were damaged by the fire and no injuries have been reported.
Firefighters says the boats did not suffer damage at the water line and are not in danger of sinking.