The nine-year-old bay gelding is part-owned by Wales rugby player Jonathan Davies and was ridden by 17-year-old Welsh jockey Jack Tudor.
The Christian Williams-trained horse was named Welsh Horse Racing Chaser of the Year in November and had been targeting the Welsh National all year. He hit the front three fences out and never looked like losing once there, with the victory also ending a 54-year wait for a Welsh winner in the post-Christmas race.
Wales and Scarlets centre Davies was jumping for joy in the crowd as he watched his horse pull clear.
“It’s an absolute dream for us,” Davies said.
“Christian has been amazing with him and deserves all the plaudits. It’s been amazing. I can’t stop smiling. I’m over the moon.”
Last year’s winner Elegant Escape had bid to become the first back-to-back winner of the Welsh Grand National in 30 years and set off as favourite on Friday. But his 11st 12lb weight – 9lb more than last year – proved too much of a burden, and despite travelling well he faded late on.
Of the 17 runners it was The Two Amigos and last year’s runner-up Yala Enki took up the running, tracked closely by Potters Corner. Those three remained the leading trio for the majority of the race, which began to develop as the horses turned for the line.
The Paul Nicholls-trained Truckers Lodge, despite jumping poorly on occasions, looked the most likely to spoil the Welsh celebration at Chepstow. But Potters Corner held on gamely and pulled clear after the final fence to take the spoils by a length and three-quarters.
Despite only turning professional in August, Tudor gave Potters Corners an eye-catching ride to victory.
Speaking afterwards, the young jockey said “I knew we had a massive chance going into it, I was always pretty confident.
“This is the biggest win so far, hopefully I’ll win a few more of these.”
Trainer Williams said the race “could not have gone any better” for Wales.
“We were a bit nervous today but I am thankful for everyone who has supported us,” said Williams.
“Any feature race is special but especially the Welsh National. He is a special horse.”