The Olympic gold and silver medallists, who took a huge 5.5-point lead into the free dance, scored 116.19 for their program to "Pilgrims on a Long Journey" by French Canadian artist Coeur de pirate, and Sam Smith's "Latch," despite a near fall by Moir. He stumbled to one knee coming out of a step sequence, prompting an audible gasp from the crowd at Helsinki's Hartwell Arena.
They finished with 198.62 points overall.
Virtue, from London, Ont., and Moir, from Ilderton, Ont., made a stunning comeback after stepping away from the sport for two seasons. They've won every one of their events this season, shattering world records along the way.
They broke their own world record in the short dance on Friday.
Tessa Virtue and Scott Moir, of Canada, show off their gold medals during victory ceremony at the World figure skating championships in Helsinki, Finland, on Saturday. (AP Photo/Ivan Sekretarev)
Moir's spill meant the Canadians lost ground to second-placed French pair Gabriella Papadakis and Guillaume Cizeron, but their five-point lead from the short dance was enough.
Papadakis and Cizeron took second with 196.04 after breaking their own record in the free dance with 119.15.
The United States won its only medal of the worlds as siblings Maia and Alex Shibutani took bronze with 185.18.
Kaitlyn Weaver and Andrew Poje of Waterloo, Ont., finished fourth with a score of 184.81. Toronto's Piper Gilles and Paul Poirier of Unionville, Ont., were eighth with 178.99 points.
Earlier Saturday, Toronto's Patrick Chan missed the medal podium in the men's competition. The three-time world champion finished fifth, falling two spots after Saturday's free program.
Tessa Virtue and Scott Moir, of Canada, skate their free dance to win the gold at the World figure skating championships in Helsinki, Finland, on Saturday. (Photo: Ivan Sekretarev/AP via Canadian Press)
Chan, who was fifth last year in Boston, scored 193.04 points for his program to "A Journey," a piece of music written by Canadian pairs skater Eric Radford, finishing with 295.16 points overall.
Japan's Olympic gold medallist Yuzuru Hanyu landed four quads for a world-record free skate score of 223.30 points and a total of 321.59 points to take gold after entering the day fifth.
Japan's Shoma Uno (319.31) won silver, while China's Jin Boyang (303.58.) took bronze.
Kevin Reynolds of Coquitlam, B.C., was ninth with a score of 253.84.
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