The success was the Spaniard’s eighth title on the ATP tour but Pouille will rue an opportunity missed as he closes in on making his debut in the top 10.
The Frenchman, who was on the receiving end of a similarly bitter defeat to Karen Khachanov in Marseille last week, led by a break in the second set but his inconsistency from the ground allowed Bautista-Agut to restore parity and close out the victory.
“I have been working a lot this month and I was prepared to manage all the emotions,” Bautista-Agut said courtside.
“This tournament is very special and it’s going to be in my heart for the rest of my life. I’m so happy I’ve won a 500 event.”
The Spaniard began the match on the front foot and he would not relinquish the upper hand until midway through the second set.
He was flawless on serve through his opening two service games before he increased the pressure on Pouille in the fourth game.
The Frenchman salvaged two break points before unloading on a thundering forehand to save the third but he was struggling to string consecutive points together. It proved his undoing when Bautista-Agut constructed a fourth break opportunity and Pouille contrived to hit a double fault.
Pouille threatened to restore the deficit but the Spaniard held off his advances to hold for a 4-1 buffer.
The double break seemed imminent for Bautista-Agut as he brought up 15-40 but Pouille held his nerve to remain within touching distance.
However, the Spaniard was serving incredibly and he would be serving for the opening frame after half an hour on court. Cannoning down another ace, he held to 15 to move ahead.
Three of Pouille’s matches this week have gone the distance and another decider seemed on the cards when the Frenchman broke for a 3-1 lead.
He botched an agonizingly straightforward volley after fashioning a pair of break points but after a lengthy deuce rally in which he prevailed, he broke the Spaniard for the first time on the evening.
His advantage was short-lived, however, as Bautista-Agut broke back immediately after a sumptuous lob that Pouille could only admire.
Both players traded holds but it was in the ninth game where the Spaniard sharpened his focus, breaking as Pouille netted a forehand to set up a crowning fashion.
It was a concluding game that was fraught with lengthy exchanges but the Spaniard prevailed and after an hour and 23 minutes, he raised his arms aloft in triumph.