Lewis' five-shot Bridgestone Challenge win was his first victory in seven years.
The Englishman carded a seven under par round of 64 to triumph at Luton Hoo Hotel, Golf and Spa ahead of Papadatos, becoming the first Englishman to lift the Bridgestone Challenge and winning for the first time since his 2011 Portugal Masters success on the European Tour.
Papadatos' runner-up finish moves him to 12th on the Challenge Tour money list and, with the leading 15 at season's end earning European status in 2019, he is well placed to graduate.
The local Bedfordshire star Lewis began the final round one stroke behind overnight leaders Stanislav Matus and Papadatos but backed up his opening rounds of 63-67-67 to claim his first European Challenge Tour title.
A bogey on the first did not trouble the 27 year old as he set his sights on glory with birdies on the following three holes to join the leaders. A further three gains around the turn saw Lewis take the lead and then extend it as the sun shone on the Bedfordshire parkland.
With the chasing pack far behind, Lewis birdied the par three 13th and par five 17th to move to 23 under par, before a tap-in par on the 18th sealed a memorable victory.
“This win means a lot. It doesn’t matter whether you win a huge event or a small event, and this is a big event on the Challenge Tour, either way it means a lot,” he said.
“I’ve probably had more fun this week then I did seven years ago. I appreciate the win a lot more now. I’ve struggled over the years and when you struggle or lose something you appreciate things more. That is something that I took advantage of when I was younger, so if I can continue to play like this and get a few more wins, then I can really appreciate what I’m doing.
“It wasn’t as easy as I thought it was going to be today. It was very windy, and the course was very bouncy. I drove it well, though, and when I was in position I was able to go at the pins and I holed the putts when I needed to.
“This win gives me a lot of confidence. I didn’t panic today, and I think that’s the big thing I can take from this week.”
Australia’s Papadatos signed for a round of 70, one under par, to claim a runner-up spot alongside Sebastian Soderberg, who recorded a round of 69, two under par. While fellow overnight leader Matus carded a disappointing two over par round of 73 to finish in eighth.
With his victory, Lewis leaps from 56th to 18th on the Road to Ras Al Khaimah. Papadatos moves to 12th, while Soderberg jumps into second place in the Rankings with six events to play.
KIERAN PRATT: 40-METRE BUNKER SHOT
Want video tips delivered straight to your inbox? Subscribe to iseekgolf.com newsletters.