The silver medallist was not among the favourites heading into the event, but took advantage when many skiers struggled to shoot clean. Windy conditions had only two athletes come away without faults.
Norway's Johannes Thingnes Boe finished a narrow 12.1 seconds ahead of the Calgary native with a time of 24 minutes, 12.8 seconds. Both competitors missed one of ten shots.
The 29-year-old continues to shatter expectations. Smith reached a career-best finish exactly a month ago when he came in fifth in a World Cup race in the Czech Republic.
The bronze medal went to the brother of Saturday's gold medallist, Tarjei Boe, who is a former overall World Cup champion.