Spaniard Granollers and Argentine Zeballos, who initially paired up in 2019, won the French Open and US Open last year and justified their top seeding, having not dropped a set in their 2026 Roland Garros campaign.
Finland's Heliovaara was error-prone with his serve throughout the match as the second seeds, who have also won two Grand Slams together, struggled to keep up with their opponents' well-placed winners from close to the net.
"I'm 41 years old (and) this is one of the best moments of my career. So it's never too late for anybody," said Zeballos, whose partner, Granollers, is 40.
A Heliovaara double fault handed the first break to the holders in the third game. Although the second seeds broke back to make it 3-3, Granollers hit two forehand winners to break in the next game, tilting the set back in the top seeds' favour.
Briton Patten began the second set with two unforced errors and a double fault as Granollers and Zeballos got another break, and the Argentine hit winners all over the court to extend the lead to 3-0, which proved insurmountable for their opponents.
"Sorry guys, wasn't the best, but thank you," Patten, 30, told his family and friends in the stands.
"Harri, thanks for being my partner. We're going to bounce back stronger, we know that," he said of the 37-year-old Finn.