Rovanpera finished in emphatic fashion, winning the final power stage at Jack's Ridge in Whitford by 0.6 seconds.
He claimed six of the 17 stages across the event.
Hayden Paddon comfortably cruised to the WRC2 title by 2m 33.1s, finishing sixth overall and winning 13 stages in his category.
Paddon capped off Rally New Zealand by winning the power stage in the secondary class, coming in 0.5s ahead of Kajetan Kajetanowicz.
"It's a big tick in the box this year," Paddon said. "Pleased the pressure is off of actually doing this because we would've looked not so good if we did something silly. Very happy to get this done."
Supercars champion Shane van Gisbergen placed third overall in the WRC2 class, 3m 25.1s off the pace.
"It's not tough, it's fun. I'm driving a rally car in the World Rally Championship, it's pretty cool. I'm living my dream and to get a podium, I'm stoked. I've had a ball," said van Gisbergen.
There was no shortage of aggression from Rovanpera to start the day, winning the day's opening stage through Whitford Forest to extend his lead over Ogier.
Tanak went full throttle as the drivers got their first taste of Jack's Ridge in stage 15, where the Estonian ousted the Finn by 1.7 seconds.
Ogier was content to let his Toyota teammate remain in front, with his main objective holding off Hyundai's Tanak to secure the one-two finish for the manufacturers' championship points.
But that did not stop the Frenchman from winning stage 16, edging Rovanpera by 0.8 seconds and Tanak by 2.6.
Paddon won three of the four WRC2 stages on Sunday and relished the atmosphere at a sold-out Jack's Ridge.
"The driving is almost secondary to the amount of people that are here. It's just awesome to see rally in New Zealand so well supported; I think the best it's ever been supported. New Zealand's put on a good show."
Rally chairman Peter Johnston has confirmed Rally New Zealand will not feature in the WRC next year, but discussions have begun to secure its return in 2024.
