The veteran pair had the best score in the free skate to secure a total of 193.86 points. World bronze medalists Meagan Duhamel and Eric Radford of Canada finished second with 190.89.
"I was very excited because we got the gold medal," the 34-year-old Tong said. "This gold is very important for us because it's our final season."
By finishing second, the Canadians secured their place in the Grand Prix Final, which features the top six skaters in each category.
Americans Caydee Denney and John Coughlin took the bronze medal with 184.01 after overtaking Russians Vera Bazarova and Yuri Larionov, who were third after the short program.
Coughlin was impressed by the boisterous crowd.
"I didn't realize how noisy it would be, it was like a soccer crowd out there," he said.
Duhamel hopes to finally win in Paris one day.
"I've got two bronze and two silvers here and I want to win the gold, so hopefully they'll invite us back," the Canadian said.
Later, three-time world champion Patrick Chan, defending champion Ashley Wagner and ice dance Olympic champions Tessa Virtue and Scott Moir were set to defend their overnight leads.