The American carded a closing three-under 68 at Quail Hollow to finish the tournament on eight-under and win his first major by two shots from joint runners-up Francesco Molinari, Patrick Reed, Louis Oosthuizen and 54-hole leader Kevin Kisner. 

Rickie Fowler and WGC-Bridgestone Invitational winner Hideki Matsuyama were a further shot adrift on five-under.

It was 24-year-old Thomas' third win of a remarkable 2017 and comes less than two months after he blew the 54-hole lead at the US Open. 

Impressively, he is the third consecutive American under the age of 30 to win a major. 

Consecutive majors won by 2 different players 24/younger (last 2 instances)

1923: B. Jones/Sarazen
2017: @JordanSpieth/@JustinThomas34

— Justin Ray (@JustinRayGolf) August 13, 2017

"I had an unbelievable calmness throughout the week, throughout the day," said Thomas afterwards. " I truly felt like I was going to win. I remember my girlfriend was supposed to fly out at about 7:00 and I was like, "You need to change your flight to later, because I don't know, I just feel like I don't want you to miss this. I feel like I'm going to get it done.

"I just was very confident. I didn't get flustered. I felt like I kind of kept everything in

front of me. I know how hard doubles are to make up out here, so I tried to avoid those and was able to make a lot of birdies. It was great."

As the son of a PGA professional, Thomas admitted it was extra special to win this particular championship.

"It was something that obviously as a kid growing up, being a golf fan, you want to win all the majors. You want to win any major," he added. "[But] for me, the PGA definitely had a special place in my heart. It's just a great win for the family, and it's a moment we'll never forget, all of us."