The 2016 Masters champion went into the final round at St Andrews with a three-shot lead and carded a 68 to get to 18 under and win by two from fellow Englishman Tyrrell Hatton and Joakim Lagergren of Sweden.
Willett extended his lead to four in the early stages and – while he was briefly reeled in by Richard Bland – birdies at the ninth and 10th handed him a three-shot advantage once more and eight pars on the difficult closing stretch saw him close out a first victory in two years.
Following his triumph at Augusta National, Willett slipped to 462nd in the world before winning two of the European Tour’s elite Rolex Series events in 2018 and 2019.
This season has seen him struggle with Covid-19, wisdom teeth, appendicitis and a hernia but he has once again bounced back to win his eighth European Tour event and could move back into the world’s top 100.
“It’s been a couple of years of average stuff again,” said Willett, who turned 34 on Sunday.
“It’s been a very unfortunate last eight months. Every time the game feels like it’s been in a nice place, we’ve had a couple of things, issues with health, just things that you can’t really avoid.
“They seem to have knocked us back a peg or two and we’ve never really been able to get the momentum going in.
“For everyone watching, this seems quite out of the blue, but the practice I’ve been doing at home and the inner belief we have every time we get in and out of position to do something was proven again.”
Willett admitted he was ‘bitterly disappointed’ to not be involved in the Ryder Cup at Whistling Straits last month, but would love to represent Europe again in 2023 after featuring in 2016.
“It wasn’t nice to watch the guys get beat when you know that you think you can add something to the team. But I wasn’t playing well enough to get on the team,” he said.
“I very rarely do long-term goals but I would definitely love to be on that team in two years’ time to try and help out.”