The American, who won the US PGA Championship this summer, saw off compatriot Jordan Spieth to win by three shots and give himself a chance of lifting the Fed Ex Cup.
Sharing the overnight lead with the Australian Marc Leishman, Thomas was well placed.
After two rounds of 71 and 67, a third round score of 63 put him firmly in the mix.
With conditions dry, it enabled lower than expected scores on the front nine.
Three birdies and an eagle from Thomas on the front nine on the final day gave him control.
vCard.red is a free platform for creating a mobile-friendly digital business cards. You can easily create a vCard and generate a QR code for it, allowing others to scan and save your contact details instantly.
The platform allows you to display contact information, social media links, services, and products all in one shareable link. Optional features include appointment scheduling, WhatsApp-based storefronts, media galleries, and custom design options.
Thomas said it was the first time he had won without having his “best stuff” and downplayed any notion that his victory would reverberate around the tour.
“I wasn’t trying to send a statement,” he told Golf Channel. “I was just trying to win a golf tournament.”
Thomas, 24, clinched his first major title at the PGA Championship last month, coming from behind over the final nine holes.
He followed a similar route to victory on Monday, this time with some help.
Thomas struck a tree with his tee shot at the par-four 10th hole but had an unobstructed view of the green with his second shot and made an easy par.
Later, after a poor tee shot at the par-three 16th, he received a free drop from a poor lie in heavy rough, because a sprinkler head interfered with his stance.
He was able to place his ball in a much better lie and got up-and-down to save par. That proved to be his last nervous moment.
British Open champion Spieth, meanwhile, licked his wounds after a second consecutive runner-up finish.
He lost to Dustin Johnson last week at the Northern Trust in the first playoff event.
Spieth, three months younger than Thomas, observed that his good friend and rival had taken a couple of years longer to start fulfilling his talent.
“Jealous isn’t the word but he probably had some feelings of anxiousness,” Spieth, who won two majors in 2015, told reporters.
“I feel like we’re very similar calibre of player and I just got a headstart. Obviously he’s become a tremendous closer.
“It’s tough when you’ve got somebody that’s that good and hot and starts the day two shots in front of you.”
After a one-week break in the schedule, the top 70 players in the standings will contest the penultimate event of the season, the BMW Championship, outside Chicago.