Beckham was the only Galaxy player to convert, firing his spot-kick into the roof of the net as Seoul goalkeeper Kim Ho-jun saved the other four.
The former England captain played the full 90 minutes and was in the thick of the action of a surprisingly physical match, creating the opening goal for the MLS outfit.
Galaxy depart for Shanghai on Sunday morning for the next leg of their tour against Shanghai-Hong Kong United on March 5, before facing Hong Kong SACC in Hong Kong four days later.