Fellow Englishman Barker had pulled off the result of the tournament on Thursday night after ending a run of 12 straight defeats against Sheffield’s world No2 and tournament top seed Nick Matthew in the semi-finals.
But the 29-year-old admitted that he was unable to “back it up”, coming up against an impressive Willstrop, who clinched the 17th PSA Tour title of his career with an 11-8, 5-11, 11-4, 11-4 triumph in just under an hour.
“Winning titles at this level is getting harder and harder,” said Willstrop. “The effort you need to put in is immense.
“This is one of my favourite venues - I love playing in the Canary Wharf Classic,” added Willstrop, who has played in every event since first winning it in its first year back in 2004, following it up with further successes in 2007 and 2008.
“It’s incredibly tough following a win like he (Barker) had last night (against Matthew). Any win against Nick is like winning an event!
“But he didn’t show any signs of it today. It was really tough. He made the court very long and hit the ball into all the spaces.
“I got a good start in the third game, which was very important.”
Barker began the stronger, winning the first four points, before Willstrop took control of the opening game to win 11-8.
The second game went the way of Barker who enjoyed more consistency but, from 7-4 up in the third, Willstrop’s ability to win 10 straight points to give him a 6-0 lead in the fourth effectively sealed the game.
The 29-year-old from Leeds even had time to throw in a few attempts at matching the amazing triple-fake shot he produced in the recent Davenport North American Open and launched an internet sensation.
Barker, the No 4 seed, admitted he didn’t quite have enough to repeat his heroics of the previous night.
“You saw tonight just how good a player James is,” said Barker.
“It was a good win for me last night (against Matthew), but I couldn’t back it up.”