Overnight leader Valimaki, who had two runner-up finishes over the past two seasons, closed with a four-under 66 to edge out American Max McGreevy who stormed home with a 63.
A two-time winner on the European tour, Valimaki earned a two-year exemption on the PGA Tour and is assured of playing the first two $US20 million signature events of 2026 by finishing at No.51 in the FedEx Cup.
Far more dramatic was everything going on in front of Valimaki.
The top 100 in the FedEx Cup standings — down from 125 players in previous years — have full PGA Tour cards for a 2026 season when the fields will be smaller.
American Ricky Castillo closed with a 62, and when he finished, it looked like that would be enough for him to move from No.135 inside the top 100.
But then McGreevy holed a 30-foot birdie putt on the final hole, moving him into second place alone with Castillo outright third and down to No.102 by fewer than 10 points.
Right after McGreevy holed his putt, Lee Hodges had a 10-foot birdie attempt that narrowly missed and cost him a chance to move into the top 100. The par for a 66 left him at No.101 in the FedEx Cup standings by about two points.
When the RSM Classic ended, the players at Nos. 95 to 100 going into the final event were unchanged, with Australia's Karl Vilips (68, tied 51st) hanging in at No.100, though he already had a two-year tour exemption after his victory in Puerto Rico early in the year.
Fellow Aussie Harrison Endycott closed with a 68 to be tied 34th but was well out of card contention sitting outside the top 200.
The 27-year-old Valimaki was thrilled with his breakthrough win.
"It has been a long road, of course," Valimaki said. "I feel like it's a really tough year even when I kind of played decent golf, and then to keep pushing and find some good grooves in the last few tournaments, it feels amazing."
McGreevy, who already had his card locked up, moved up to No. 60 to also qualify for a pair of signature events to start next year. His finish bumped Jordan Spieth, who did not play this fall, from the 60th spot, meaning Spieth will need sponsor exemptions for Pebble Beach and Riviera.
Colombia's Nico Echavarria shot 65 to tie for fourth and moved into that No.51-60 slot for signature events on the West Coast.
Sam Stevens made a hole-in-one on the third hole and wound up with a 63 to join an 11-way tie for seventh place. He already was set for all the signature events. On his mind at No.48 in the world ranking was staying in the top 50 at year's end to earn a spot in the Masters.
It's too close to call, as it is for Johnny Keefer, the Korn Ferry Tour player of the year who came into the week at No.50. Both were in that big tie for seventh and figure to move up a few spots, with tournaments still to be held in Australia and South Africa the rest of the year.
