While Noh, the leader through three rounds, never fell out of first, he did make his first three bogeys of the tournament and briefly fell into a tie with
But Bradley did himself in with a bogey on the fifth hole and a triple bogey on the sixth, while Noh remained steady enough to hold off remaining challengers.
The 22-year-old South Korean player, the youngest winner this season, wore yellow and black ribbons on his hat to honor the more than 300 dead or missing in a ferry accident in waters off his home country.
After taking the third-round lead and becoming the first to play 54 holes at TPC Louisiana without a bogey, he said he hoped he could string together one more bogey-free round and come through with a victory to lift the spirits of his nation.
He accomplished the second part, and he'll take it. His best finish in 77 previous PGA Tour starts was a tie for fourth at the 2012
The seventh first-time PGA Tour winner in the last 10 years in the event, Noh finished at 19-under 269 and earned $1,224,000.
Andrew Svoboda and Robert Streb tied for second. Svoboda had a 69, and Streb shot 70.
Bradley would up with a 75 to tie for eighth at 13 under.
Poised and unflappable, Lydia Ko birdied the final hole for her third
It went down to the final shots, and the teen made a six-foot birdie putt for a three-under 69 moments before Lewis knocked in a four-footer of her own to finish one stroke back at 11-under 277.
"The 18th hole I knew how loud the claps were and that I needed to get close and give myself a birdie chance," Ko said.
After beginning the day a stroke behind Lewis, Ko birdied three of her final four holes on the front nine on the way to and 12-under 276 total at Merced Lake Golf Club.
Alexander Levy of France held on to win his maiden European Tour title at the China Open in Shenzhen, recovering from a late double bogey to shoot a 69 and beat Tommy Fleetwood by four strokes.
The 23-year-old Levy, playing in his second year on tour, vaulted into the lead with a career-best 10-under 62 in the second round, then held off a late challenge from Fleetwood in the final round to take home his first trophy. He carded a 19-under 269 overall.
Fleetwood, who was trying for his second European Tour title, pulled within one stroke after a birdie the 17th hole, but Levy closed with back-to-back birdies to seal the win.