Home hero Jon Rahm delighted the huge crowds at Centro Nacional de Golf as he became the sixth Spanish player to win the Open de España.
The World Number Four carded a closing 67 to get to 20 under and hold off the challenge of countryman Nacho Elvira and overnight leader Paul Dunne for his third European Tour title.
His three wins have come in just 19 events, making him the third-fastest player to reach that mark, and he joins countrymen Antonio Garrido, Seve Ballesteros, Sergio Garcia, Alvaro Quiros and Miguel Ángel Jiménez as Spanish winners of the event since it joined the European Tour in 1972.
The victory is Rahm's first as a professional in his homeland after claiming seven national amateur titles at various age levels and adds to his two Rolex Series triumphs in Ireland and Dubai last season.
"It's such a satisfying feeling," he said. "When I made the decision to come straight from Augusta it wouldn't be to just show up and walk around, I wanted to win this tournament.
"I've been blessed to be national champion from 16 to all ages in Spain. To round my amateur and pro career together in this way and win the last one I had to win and join that prestigious list of Spanish winners, it's hard to explain how good it feels and how satisfying it is.
"It's been amazing. It's truly been the hardest Sunday I've ever had in any tournament that I've won because the crowd wanted it so much and I wanted it so much. You can tell how excited everybody is, I felt that tension, I felt that stress, I felt everything magnified. They payed a huge part, I came for them mainly so I'm just glad I can win this one for the Spanish people."
Irishman Dunne signed for a closing 71 to finish at 18 under, a shot clear of Elvira and two ahead of South Africa's George Coetzee.
Rahm played a beautiful chip at the first to set up a birdie and when he hit a huge drive on the second to set up another gain, he was in a share of the lead with Dunne.
Elvira also birdied the par five first and there was very quickly a three-way tie for the lead at 17 under.
Rahm soon found himself in the solo lead as Elvira and Dunne both missed the green and failed to get up and down on the fourth but Elvira snatched top spot with an eagle on the next, holing a downhill left-to-righter from 35 feet.
I came for them mainly so I'm just glad I can win this one for the Spanish people - Jon Rahm
Dunne made a birdie after a nice chip on the par five to get back to 17 under but Rahm moved away from him again, leaving himself a flick in and holing from four feet for a birdie on the seventh.
The 23 year old was once again the solo leader when a poor approach to the sixth led to an Elvira bogey but Rahm bogeyed the ninth and there was a three-way tie for the second time.
Rahm did not look likely to take advantage of the par five tenth after sending his second right and his third over the green but he chipped in and led on his own, with Dunne hitting back on the same hole when he got up and down from a bunker.
Dunne dropped a shot on the 11th after leaving himself in a nasty spot with his second and when Rahm hit a huge drive up the 13th and got up and down from 12 feet, the lead was two shots for the first time in the round.
Elvira soon changed that, holing a ten-footer on the 13th and a monster on the next to tie the lead and, with Dunne making a bogey on the 14th, a Spanish win was on the cards.
Dunne bounced back on the next to stay in contention but Elvira found the water for a double-bogey on the 17th and with Rahm birdieing the last, the title was sealed.
Dunne also birdied the last to take second place on his own.
Coetzee equalled the lowest round of the week with a 63.
The Tshwane Open champion birdied the first, second, fifth, sixth and eighth to turn in 31 and then eagled the tenth, adding further birdies on the 13th and last.
Spaniard Jorge Campillo and Scot Marc Warren carded closing rounds of 69 to finish at 15 under alongside Australian Brett Rumford, who finished with a 71, and Swede Henric Sturehed who shot a 72.
Frenchman Julien Guerrier, South African Jacques Kruyswijk and Japan's Hideto Tanihara finished six shots off the lead.