Poppleton chipped in on the second play-off hole at Frilford Heath to defeat South Africa’s Wilco Nienaber, who had tied with the Yorkshireman on 16-under-par 272.
Nienaber's attempt to equal him and extend the play-off hit the hole and lipped out to bring atonement for Poppleton.
In last year's English men's amateur semi-final at The Berkshire Poppleton called a ruling on himself as he had left a training club in his bag. He was penalised with the loss of two holes for carrying a non-conforming club - and would lose by one hole to eventual champion Todd Clements, of Braintree.
Yesterday brought more drama as Poppleton closed what was a five-shot gap on Nienaber at one stage with the aid of an eagle at the 324-yard 16th, where he drove the green and holed from 15ft.
He added a final round of 67 to his previous scores of 66 72 67 while Nienaber, who had led Poppleton by two shots after 54 holes, carded 67 71 65 69.
Poppleton was playing in the group ahead of the South African in the final round and had got to 14 under after 12 holes, but felt he needed something more so took driver at 16 and it paid off spectacularly.
At 16 under par he had moved in front, but Nienaber holed an eight-footer for birdie on the last to force the play-off only for Poppleton to prevail in the sudden-death climax.
Lindrick's Bailey Gill shot progressively lower scores of 71 69 68 67 to finish on 13 under and tied for third place with Jack Cope (The Players Club).
Twenty-four-year-old Poppleton had been chasing Nienaber for most of the final round. The South African No 1 had blitzed round in the morning in seven-under 65 and pushed the accelerator all the way to the floor early on in his second round.
He was five under after seven holes, 18 under par, and at that stage was five shots clear of Poppleton. But a bogey on the short 11th, where he missed the green, and a double bogey on 14, where he lost his drive in the gorse, pulled him back to 15 under.
Then came Poppleton's eagle at 16, and the England international commented: “I knew I needed to make something happen on the 16th. You need something like that to get you across the line and that was the turning point.”
This is Poppleton’s first international title and he said: “It means a lot, this is the pinnacle of stroke play for England Golf and a lot of fantastic players have won this.”
He added: “It’s nice to start the season off hot. I’ve had a couple of seasons when I came out really slowly so it’s good to get one early.”
Recent winner of the Danny Willett Salver, he was accompanied throughout the championship by caddie Alex Stubbs, who was also on the bag when he reached the semi-finals of last year’s English amateur.
The final day of the championship - which was won by Meltham's Jamie Bower, also in a play-off, two years ago - was marked by low scoring. Andrew Wilson (Darlington) set a new course record of nine-under 63 in the third round, which propelled him into contention.
Third-placed Cope won the Henriques Salver, awarded to the best player from GB&I aged under 20 on the first day of the championship. He was four clear of Arrun Singh Brar (Parkstone).