De Minaur downs Paul to take Mexico Open crown
The 24-year-old de Minaur fought back after dropping the opening set to clinch the seventh title of his professional career with a 3-6, 6-4, 6-1 victory.
The win was the seventh title of de Minaur's career and his first in an ATP 500 event.
It was another battling fightback from de Minaur, who had also recovered after dropping the opening set of his semi-final against Holger Rune on Friday.
De Minaur's dogged performance was epitomised by the opening game of the final set, when he saved five break points to hold before winning in 2hr 27min.
"It feels great, it feels amazing," De Minaur said in an on-court interview following his win.
"I know the hard work that's put in to be here and it's good to see the results.
"It's not always that you win the tournament and you get to finish a week unbeaten, so I'll definitely cherish this going into Indian Wells and Miami."