Despatie qualified for the Games in the men's individual three-metre event a day earlier by finishing eighth in the preliminary round.
The two-time Olympic silver medallist is back competing after having missed nearly a year with a knee injury and has only been training for a month.
"Today was a really special day," Despatie said. "This morning in the semifinals I felt liberated, I could focus only the technique, one dive at a time. I was really, really enjoying myself as well and it's been a long and tough road to get here with my injury."
Despatie finished with a score of 511.95. China's Chong He won gold with 553.35 points, while compatriot Kai Qin took the silver 524.00 points.
"It was an incredible day," Despatie said. "The level of the diving is incredibly high and I was able to be part of the that, but it's 9s, 9.5s and 10s if you expect to win and that's what I'll have to be working on in the next few months."
Despatie has competed at the last three Summer Games and is still looking for that elusive Olympic gold. The 26-year-old won silver on the springboard at the 2004 and 2008 Games after finishing fourth off the platform at the 2000 Olympics.
The Aquatics Centre venue where the World Cup is being held this week will host four events at this summer's Olympics, including diving.
Regina's Reuben Ross, who finished 10th with 455.85 points Wednesday, was pleased with his finish but is hungry for more.
"I made a strong impression with the judges and they know who I am going forward," said Ross, who also qualified a spot for Canada at the Olympics in the event after an 11th-place showing in the preliminaries. "I was 10th but as a competitor I want more and I'm going to be looking at improving those scores over the next few weeks."
In the women's 10-metre synchro, Filion and Benfeito produced the best international result of their career and also earned an Olympic spot for Canada in the event.
"Today we had an absolutely amazing day," said Filion, who along with Benfeito were sixth after the preliminaries. "We did absolutely everything we could. Our synchronization was great, our individual dives were amazing and getting the silver medal was really the icing on the cake."
Ruolin Chen and Wang Xin of China took the gold with 359.58 points, Filion and Benfeito followed at 331.65 and Sarah Barrow and Tonia Couch of Great Britain were third at 314.40.
On Monday, Despatie and Ross earned another spot for London with a fifth-place finish in the men's three-metre synchronized event.
In diving, athletes secure places for their country in each event with the final list of Olympic competitors to be determined at national trials. But barring injuries, the same group will likely be diving at the Games.