Casey took a commanding lead late in the morning round, kept his foot on the pedal and cruised to a 10-and-8 win in the 36-hole final. It was the largest winning margin for a final match in the event's history.
For his impressive Match Play debut, Casey earned more than $1.86 million -- the most lucrative winner's check in the world among officially sanctioned events.
'I'll stick it somewhere very, very safe, I'm sure,' he joked.
The financial windfall moved Casey ahead of David Howell on the European Tour Order of Merit, ending Howell's bid to become the first player to go wire-to-wire as Order of Merit champion.
Casey competed like the No. 1 player in Europe this week.
Before Sunday's handling of Micheel, his victories came against Retief Goosen, Mike Weir and European Ryder Cup teammate Colin Montgomerie.
Casey didn't play more than 33 holes in any of those matches and was never more than 2-down. Montgomerie, the only former champion who made the semifinals, never even held a lead against Casey on Saturday.
Heading to the K Club for his second Ryder Cup next week, Casey is peaking at the right time.
'Maybe desire, maybe a little bit of luck,' Casey explained his exceptional play. 'This week has been wonderful preparation for next week.'
Micheel's dubious defeat shouldn't overshadow an impressive and surprising run that included strong wins over world No. 1 Tiger Woods and world No. 10 Luke Donald.
'I'm playing well and I'm not going to let today or any other day ruin it for me,' said the 2003 PGA champion.
Micheel played steadily on the first nine holes, collecting a pair of birdies, but Casey had four birdies in the same stretch to go 2-up around the turn.
'I thought it was important to win one hole early or two holes just to get some momentum,' Micheel said. 'But he struck the ball beautifully and made a lot of nice putts.'
With a birdie at the 11th, Micheel pulled within 1-down. But the match took a turn in Casey's favor -- and remained there -- when Micheel badly botched the par-4 16th despite hitting the fairway while his opponent found a fairway bunker.
Micheel fired his approach over the green and against the grandstand and was given a free drop. But he lined his third shot past the hole and off the front of the green.
Casey won the hole with a bogey, then carried a 3-up lead into the break after taking the 17th with a birdie.
He moved 4-up with a 16-foot birdie putt at the 20th hole, the par-3 second at the Wentworth Club, then took a 5-up advantage with another birdie two holes later.
Casey only needed to two-putt from 16 feet to win the 24th hole with a par and take a 6-up lead. He ended the match by winning four straight holes with a birdie, including a seven-footer at the 25th hole.
Afterward, a lot was made about the falloff of Micheel's game from the first three rounds.
'Unfortunately, Shaun didn't play the best golf. But he's a hell of a competitor and he'll be back,' Casey said.
Micheel lamented his Sunday mistakes, talked about what a frustrating day it was and tipped his cap to Casey for playing well.
'It's always disheartening when you make it this far and don't play well,' he said. 'Maybe it was fatigue, but I don't feel fatigued. I had a nice week here. It was just a little disappointing to not take this thing to the end.'
Casey now has seven career wins on the European Tour, including three this year. He and Johan Edfors are the only three-time winners this season.
'I really wanted to win this,' Casey said. 'Yesterday, I was just happy to be in the final. Today, I'm happy to have my hands on this trophy.'