The 45-year-old started his day with a bogey, but was flawless thereafter, signing for a five-under 66 on the Coronet course at Millbrook Resort.
It left him tied at the top of the leaderboard with American Kevin Na, who made a flying start to life after LIV Golf.
Heavy overnight rain caused the start of play to be pushed back by three hours, meaning many of the afternoon starters will need to complete their opening rounds on Friday.
South Australian Ormsby has plied his trade on a number of tours throughout his career and was a late call-up to LIV Golf Adelaide earlier this month, replacing the injured Phil Mickelson.
But he is still chasing a maiden win on the Australasian Tour and would dearly love to tick that ambition off this week.
"It was pretty tough out there early - cold and wet and windy," said Ormsby.
"I was just trying to put it in damage control at the start and I played some pretty good golf towards the end there so I'm happy."
Playing his first tournament since becoming the first LIV Golf team captain to be dropped, Na signed for a bogey-free 66 on the Remarkables course to be tied atop the leaderboard with Ormsby.
The American was even able to make light of a slice of bad luck on his 10th hole, when his second shot cannoned into his amateur partner's ball, costing him at least 70 metres.
"When I saw the weather forecast I was like 'oh no, I've got the bad draw'," said Na, who has won five times on the PGA Tour.
"It wasn't easy, there was a three-club wind with the rain at times.
"I know the wind has died down, the rain has gone away and it's going to play a lot easier in the afternoon but I did the best I could in the morning."
Na was replaced by An Byeong-hun on the  LIV Golf Tour in January after the decision was taken to rebrand the Iron Heads team as Korea Golf Club.
Rising Kiwi star Kazuma Kobori was in outright third spot at four under after a round of 67 highlighted by a hole in one.
The DP World Tour player holed out with a 4-iron on the 210m 4th hole on the Remarkables course, only three months after he achieved the same feat on the party hole at the Australian PGA.
"It's actually playing pretty tricky here," said Kobori.
"I thought someone was going to go ballistic out there but no one has so far. So four under is pretty good.
"I made a few sloppy mistakes but we can tidy that up over the weekend."
Defending champion Ryan Peake, LIV Golf star Lucas Herbert and fellow Australian Anthony Quayle were among the prominent afternoon starters.
