Riding the eight-year-old bay gelding Torino, Michael was more than half a second faster than Simon Crippen, who finished runner-up.
"It's my second time competing at Hickstead and my second win here so if we keep up this trend I'll be happy," said 19-year-old Michael, who also won the All England Grand Prix last September.
Michael is originally from Co Galway but moved to Hickstead last summer to be the stable jockey for Shane Breen. He moved yards recently but remains close to the All England Jumping Course, being based a few miles down the road in Bolney, West Sussex.
Scottish rider Douglas Duffin made an 11-hour drive to Hickstead worthwhile by scoring a double of wins in the International Arena.
Earlier this morning Douglas won the Hickstead Novice Championship with Aslan II, then he also won the big class of the afternoon - the Bunn Leisure Derby Tankard - with Quidam B Z.
"His rideability is improving all the time, he's got all the talent and he's super careful too," he said of the nine-year-old bay stallion, who finished four seconds faster than Tina Fletcher and Hello Sailor.
"I pushed him as fast as I felt he was comfortable with. It was the horse's first time in the main ring - a lot of horses can go in there and back off and lose a little bit of scope but he didn't," Douglas added.
"Hickstead's always been my favourite show to compete at. I've won here a few times and that's why I keep coming back."