Petri used his superior power and swinging left-hand serve to set up many points, but Kingi was able to remain competitive with his consistency off the ground.
They split the first two sets, with Petri taking the first 6-4 and Kingi the second 6-3, but the vital break came at 3-2 in the third when Petri took advantage of some indecision and broke Kingi's serve.
He then ran through his own serve comfortably to lead 5-2 and served out the match to finish 6-3.
Both men hit the ball with fierce power and contributed to many exciting rallies.
In the semifinals, Petri was stretched to the limit by his doubles partner, Patricio Angelone, an Argentinian based in Christchurch.
Petri won 6-4, 7-5 but the match was played with high intensity for over two hours.
Kingi was a little too consistent for Czech student Jan Carboch and held on to win 6-4, 6-3.
Both claimed a number of cheap points with big serves, but Kingi was able to pressure Carboch into errors at key points in both sets.
The women's round-robin event went to Otago's Georgia Hume who beat Brittany Fisher (Canterbury) 6-0, 7-5 in the final round.
Both were otherwise unbeaten.
After dominating the early exchanges Hume began to make more errors in the second set but held her game together better from 5-5.
The mens doubles finals went to Petri and Angelone who beat Kingi and Jono Ussher 6-1, 6-1.
Rafael Nadal left no doubt that he would be the overwhelming favourite at next month's French Open after crushing fellow Spaniard David Ferrer 6-2 6-3 in the Monte Carlo Masters semifinals yesterday, Reuters reports.
Compatriot Fernando Verdasco, the sixth seed, was be the last man standing in Nadal's way to a record sixth consecutive title in the glitzy principality after he demolished world No 2 Novak Djokovic 6-2, 6-2 in the other semifinal.
Four-times French Open champion Nadal, who has not won an ATP title in the past 11 months, was again in a class of his own on the Monte Carlo clay.
After needing just 75 minutes to dismiss Ferrer, Nadal took the time to sign a few balls and fire them into the delighted crowd as the first sunbeams pierced through on a mostly cloudy day at the Monte Carlo Country Club.
"I am playing very well. I think I played a very good match today," Nadal said.
