The Texan wobbled a bit in the closing holes, but did enough early to hang on for a one-under-par 70 on the brutal Bethpage Black course in NY to seal a one-shot victory at nine under.
The victory was the 26-year-old's first on the PGA Tour since his triumph at the Hyundai Tournament of Champions in January 2015, and he had double reason to celebrate in NY, with the triumph also earning him an automatic spot on Davis Love III's Ryder Cup team. Patrick Reed entered the week eighth in the standings and easily maintained his spot on the team with a one-stroke victory, his first of the season. "It takes care of everything".
Fowler still has a reasonable chance to be at Hazeltine on September 30 for the Ryder Cup because Davis Love III doesn't make his three captain's picks until after the next two FedEx Cup playoff events.
Five of the spots were already clinched going into The Barclays U.S. Open champion Dustin Johnson, Jordan Spieth, Phil Mickelson, PGA champion Jimmy Walker and Ryder Cup rookie Brooks Koepka. Reed held off the rest of the field on the Black Course in the final round and ended the 72-hole event with a 275 (-9).
Two shots behind with four holes to play - and two shots clear of third place - Fowler missed a 4-foot par putt on the 15th hole and made double bogey on the next hole.
Love said his statistics company predicted that would be the case this year, even though Fowler was poised to qualify until dropping three shots on the last four holes. But his drive on No. 18 landed in a left-side fairway bunker and he settled for a bogey to seal the one-shot victory.
Love stressed the importance of the eight qualifiers, at one point saying it was time for them "to take ownership of the team".
"It was very important", said Reed, who played on the 2014 US team that was dominated by Europe in Scotland.
Fowler was at nine-under 204 overall and had a slim lead over 36-hole leader and fellow American Patrick Reed, who shot a 70.
Reed later said that short stretches of poor play had cost him several chances to win in recent times, but the difference on Sunday was that he had a cushion coming down the stretch.
O'Hair was among five players who moved into the top 100 in the FedEx Cup, advancing to the next playoff event at the TPC Boston that starts Friday.
Marc Leishman, 57 at the start of The Barclays, missed the cut and fell to 71 and while guaranteed a place next week will need to play well to survive to week three. According to the PGA Tour website Fowler has also earned almost $2.5 million dollars this year. In that stretch, Reed finished second in three tournaments.
The 20-year-old shot a 6-under 66 to beat Sei Young Kim (65) of South Korea by four strokes. And he could guarantee his spot on the team with a second-place finish. It also secured a spot on the United States team for next month's Ryder Cup.
As the contest came to a climax, three more Americans - Gary Woodland, Sean O'Hair and Ryan Moore - were clustered with Australian Jason Day three shots off the lead but running out of holes.