Fifth seed Rublev, who also won the title in 2020, claimed his first tournament win since his triumph at the Madrid Open last April, but was made to battle for the crown, just as he had all week.
In the quarter-finals, he had survived a match point against Alex de Minaur and only prevailed after the Australian had saved seven match points. In the semis, he was taken to another final-set tiebreak against Felix Auger-Aliassime.
"It feels amazing. It's the first time I've won the same title twice," a delighted Rublev said.
"I'm really happy. I don't know what else to say."
The opener went with serve for the first 11 games, with Rublev serving to love on four occasions and Draper twice doing likewise, before the Russian finally broke the Briton to take the first set.
The second set appeared to heading towards a tiebreak when Draper managed to break for a 6-5 lead and served out to level the match.
Draper had never beaten Rublev in their three previous meetings, and went into the deciding set with the wind in his sails, but Rublev showed no mercy.
Rublev broke twice early on to storm into a 5-0 lead and while Draper managed to avoid a bagel, the Russian fired down two aces to wrap up the win.
"I really like Jack as a person and I really like his game. He has a really, really great career and future ahead. He will win many great things," Rublev said.
Draper failed in his bid to win his third ATP title after winning in Stuttgart and Vienna last year, but the 23-year-old's run to the final will lift him to a career-high 12th in the rankings.
"He was too good today. Outlasted me," Draper said.
"We played some really tough matches this week. In the third set he was a bit too strong for me."
16°C