Fleetwood fired a final-round 65 to finish 22 under par, two shots clear of fellow Englishman Ross Fisher.
It was the 27-year-old’s fourth European Tour victory and came just two months after he was crowned the 2017 Race to Dubai champion.
“I’ve put in a lot of work, I wanted to prepare for this year like I didn’t win the Race to Dubai,” Fleetwood said.
“It was important to come out and make sure I’m hungry. I wanted to do the right things, and whenever you win it is validation that you can do it.
“My best golf is getting better and better and my worse golf is getting better as well.”
Fleetwood’s victory could put him in the top 10 of the world rankings for the first time when the new list is published today.
Fisher, who had held the overnight lead with Thomas Pieters, seemed to be on his way to a first European Tour victory for nearly four years after picking up four shots in the outward nine.
But European number one Fleetwood produced an incredible birdie blitz to come home in 30 shots.
“I just had the lines going really well,” Fleetwood said after a round which featured eight birdies and only one bogey.
“I played great this week, especially today because you knew it was going to be tough. It’s a funny feeling coming to defend a title as I’ve never done it before.
“You get here on Monday, see the trophy and don’t want to give it back.
“It feels like it is yours and all week that feeling was in the back of my mind. It’s quite emotional.”
Rory McIlroy closed with a 70 to share third place with Matthew Fitzpatrick, two shots adrift of Fisher, and the Northern Irishman said he was pleased with his first event since calling an early end to his injury-plagued and winless season in October last year.
“My game’s in really good shape and I saw some positive signs, so I’m looking forward to next week in Dubai and the rest of the season,” McIlroy said.
“I’ve no doubt that if I can play next week as I have done this week then I will have a good chance. It’s been a huge success for me this week, even if I didn’t win. I’ve got a lot out of it and I’m excited to get at it next week.”
Pieters and Chris Paisley, who had won the South African Open the previous week, tied for fifth a shot behind McIlroy and Fitzpatrick.