Weaver and Poje, both from Waterloo, Ont., finished first in the free skate with 101.64 points for a combined 163.14 points in the Russian event. The pair scored 61.50 points for their performance in the short program on Friday.
Earlier, Kirsten Moore-Towers of St. Catharines, Ont., and Dylan Moscovitch of Toronto took bronze in the pairs program to also qualify for the Japan final.
Poje says he and Weaver used their disappointing short dance score as motivation heading into Saturday's event.
"After not having the most positive score on the short dance we wanted to make sure we came back and showed that we have a strong free dance ... and I feel like we did that," he said. "We didn't achieve a season's best score, but we achieved a season-best performance for us."
Weaver and Poje missed out on qualifying for the ISU Grand Prix Final last year. Now that they've secured their spot in this year's event, Weaver says that means "everything."
"It's the last time the judges are going to see us before the Olympics," she said. "We want to leave a lasting impression and show that we are every bit eligible for that Olympic podium.
"The best teams in the world will be at that final and that's our shot to measure ourselves up against them and see where we stand two short months before the Games. It will give us a very good judgement as to what we need to work on and what has gotten better since the last time we've been up against these teams."
Canada's Olympic gold medallists in ice dancing in 2010, Tessa Virtue and Scott Moir of London, Ont., have already qualified for the Grand Prix Final.
Ekaterina Bobrova faltered during her free dance with Dmitri Soloviev, but the Russians held on for the ice dance gold with a total of 168.32 points. Americans Madison Chock and Evan Bates took third place.
Toronto's Piper Gilles and Paul Poirier finished sixth with 133.66 points.
In the pairs figure skating event, Aliona Savchenko and Robin Szolkowy of Germany won gold, followed by Vera Bazarova and Yuri Larionov of Russia and Moore-Towers and Moscovitch.
Moore-Towers fell on her chest coming out of a lasso lift, which she casually characterized as one of "a couple of little weird things" in the routine.
Despite the fall, the Canadians picked up 123.08 points, staying in third place overall with 188.73 points. They will join Meagan Duhamel of Lively, Ont., and Eric Radford of Balmertown, Ont., who have already qualified for the final pairs program in Japan.
"For the most part we were strong from the beginning to the end," Moore-Towers said. "Our skating skills are improving every time out. We are excited to have made the final where we will have better performances."
Moscovitch said the pair came into the competition well prepared after some solid training since Skate Canada a month ago.
"We'll definitely be hungry at the Grand Prix Final," he said. "It's always special to make the final, especially in an Olympic year. It's an opportunity to be among the top-six in the world and competing there will set us up well for the second half of the season."
Ottawa's Patrick Chan will compete in the Grand Prix Final in the men's program.