Europe produced an overwhelming 18.5-5.5 victory over Asia - who had trailed 9-3 overnight - to become the first outright holders of the trophy after a 10-10 tie in the inaugural staging of the event in 2014.
It was Willett's point, earned with a 3&1 triumph against Korean Byeonghun An, which moved them to the winning mark.
And his fellow Sheffielder Matt Fitzpatrick also won, by two holes against Thailand's Kiradech Aphibarnrat, as Europe emphasised their superiority.
Willett was facing An for the third consecutive day, having lost to the 2015 Rookie of the Year in the fourballs alongside Fitzpatrick but beating him in the company of Ian Poulter in the foursomes, Thongchai Jaidee being An's companion on each of those occasions.
An won holes five and seven to move clear, but the European Masters champion's response was emphatic as he took three holes in a row from the eighth to go one up.
Wins at holes 12 and 15 had Willett three ahead and seemingly coasting, but PGA title-holder An prevailed at the 16th.
Undeterred, Willett responded by taking the next to close out his 3&1 win.
Fitzpatrick won the first hole against Aphibarnrat, but stood on the fourth tee trailing after two consecutive wins from the Thai.
Hallamshire GC honorary member Fitzpatrick responded in kind, winning the seventh and eighth to return to one ahead, and stretched his advantage to two at the 11th.
Back came Aphibarnrat with successive wins at holes 14 and 15 to return the match to all square, but British Masters champion Fitzpatrick showed his mettle by taking both holes 16 and 18.
He and Willett finished with two points out of three for the event, their only ceding of a point coming together on day one.
On gaining the decisive point, Willett commented: "It's really good, but I'm not really bothered who it was.
"It's nice to be me, but if it wasn't going to be me it was going to be the next person in, and if it wasn't them it was going to be the next after that.
"I think the most pleasing thing for us and for Clarkey (captain Darren Clarke) is that we came out and I don't think any one of the first six was complacent.
"They've all pulled through and played their hearts out."
Fitzpatrick commented: "My match was up and down. Kiradech threw a lot of birdies at me, and I just tried to play steady all day and keep myself in it.
"Obviously I played quite nicely - just fairways and greens was the plan all day and it paid off."
Poulter, as on days one and two, had set the tone for Europe, beating Danny Chia 4&3 to put some early blue on the board and quell any hopes of an unlikely fightback from Asia, who were six points adrift at the start of the singles.
Once his fellow Englishmen Lee Westwood and Andy Sullivan had followed Poulter's lead, beating Nicholas Fung (7&6) and Jaidee (4&3) respectively, it was left to their compatriot Willett to deliver the coup de grace.
Further victories for Fitzpatrick, Chris Wood, Kristoffer Broberg, Victor Dubuisson and Søren Kjeldsen sealed a convincing win for captain Clarke's side.
Asia's only final-day wins came through Anirban Lahiri and KT Kim, who beat Shane Lowry 2&1 and Bernd Wiesberger 3&2 respectively, and a birdie putt on the last hole by Jeunghun Wang ensured his match with Ross Fisher finished in a half.
Clarke, who will also captain Europe as they defend the Ryder Cup in September against the USA at Hazeltine, Minnesota, said: "The team have played fantastic this week. I've thrown a couple of my ideas at them and, aside from that, the team bonding that they have had has been brilliant.
"What Lee and Poults have brought to the team room has been priceless. They have been very, very good. All the young kids have listened to them, they have all learnt from them.
“So I think it's been a hugely beneficial week. I always knew this was going to be a very strong team, and the way they have played this week, I have been very, very impressed.”