The 4-year-old colt won the $6 million Breeders' Cup Classic by 2 1/4 lengths Saturday, sending rival Arrogate to a third straight career-ending defeat at Del Mar.
Collected returned $5.60 and $4, while West Coast was another 1 1/4 lengths back in third and paid $3.60.
"At at the quarter pole, it was just a two-horse race between me and Collected," Gun Runner's jockey Florent Geroux said. "We just went on and the best horse won the race."
Arrogate finished in a dead-heat for fifth with Gunnevera, done in once again at the seaside track north of San Diego.