Britain's world champion Nicola Minichiello fell victim to Whistler's 50-50 corner on her third descent, flipping over before sliding upside-down to the finish.
Leading after Tuesday's first two runs, Humphries and brakewoman Heather Moyse were cheered on by a sea of red and white clad fans in the grandstands as she produced two more error-free drives to win an incident-packed competition.
Helen Upperton, at the controls of Canada's second sled, had begun the day out of the medals but stormed up the leaderboard to seize the silver medal while American Erin Pac capped North American domination by taking the bronze.
"I wanted to take each run for what it was," Humphries, who broke the women's track record three times during the competition, said. "I'm so excited we did it."
"One-two at home, it doesn't get any better than that," added Upperton.
Humphries is Canada's second gold medallist from the sliding events after skeleton speedster Jon Montgomery's sensational victory a week ago and the celebrations were set to last into the night down in Whistler heaving bars.
As Canada's speed queens lapped up the wild celebrations in the finish area, German sledders were left scratching their heads after failing to make the podium for the first time since women's bobsleigh made its Olympic debut in 2002.
Reigning Olympic champion and top-ranked driver Sandra Kiriasis was fourth, a massive one and a half seconds off the searing pace set by Humphries while Germany's second driver Cathleen Martini crashed on her fourth run.
Martini was in the hunt for bronze but got stung by the treacherous section starting at curve 11 and her sled tottered and then tipped over at the notorious 13th curve known as 50-50, spilling brakewoman Romy Logsch in the process.
Minichiello clambered out of her bob in tears before embracing shaken brakewoman Gillian Cooke after their frightening crash.
Minichiello and Cooke, who captured world gold in Lake Placid, had plenty of work to do after the first two runs and were lying 10th before sliding down into 16th place following the crash. They did not take part in the fourth and final run.
"I’m devastated to be honest," Minichiello, who was lucky to escape injury after appearing to bang her head on the wall of the track as her sled toppled. "This is everything we worked for.
"We hit corner one again, but the rest of the run was going pretty well until we made a mistake going into 11.
"We didn't do our fourth run today because Gillian hurt her leg in the crash and because the sled was damaged.
"It's a tough track, but that's no excuse because it's the same for everyone."
Paula Walker and Kelly Thomas, Great Britain's second sled, ended up 11th.
Place of birth: Calgary, Canada
Residence: Calgary, Canada
No previous Olympic results:
Second, 2008 World Championships, Team Competition
Runner-up, 2009/10 World Cup, Women
Humphries started the sport at the age of 17. She competed in Alpine skiing for the Canadian development team in Europe before switching to bobsleigh.
Her husband, Dan, competed for Britain in bobsleigh at the 2006 Winter Olympics in Turin. He has since switched to represent Canada.
The 24-year-old’s brakeperson for her Vancouver gold was Heather Moyse, a 31-year-old rugby player who finished fourth for Canada in the 2006 Winter Games.