Playing in the afternoon with the greens still receptive after rain earlier in the week, Skinns pulled ahead with a 47-foot birdie putt on his 17th hole – the par-3 8th.
The 41-year-old was a stroke ahead of morning starters Sam Burns and Sean O’Hair.
“I drove it pretty well. I left myself in a lot of good spots,” Skinns, winless on the PGA Tour, said.
“Around here, it seems like that’s half the battle, to give yourself birdie looks.
“I was able to attack some pins that maybe if I wasn’t in such a good spot, I wouldn’t have been able to.”
Robert MacIntyre of Scotland had a 64 in the afternoon, Ryan Palmer opened with a 65, and two-time Canadian Open champion Rory McIlroy was another shot back alongside, Andrew Novak, Erik van Rooyen, Nick Hardy and Trace Crowe and New Zealand’s Ryan Fox.
Former World No.1 Adam Scott is the leading Australian in the field, his even-par 70 leaving him eight shots off the lead in a tie for 50th.
Defending champion Nick Taylor shot a 72, playing alongside fellow Canadian Taylor Pendrith and McIlroy.
Last year at Oakdale in Toronto, Taylor made an 80-foot eagle putt in a play-off to become the first Canadian to win the event since 1954.
“Usually, the morning round for me on a Thursday, there’s not that many people there,” Taylor said.
“The energy was high, which was great, gets the adrenalin going, which is fun that early in the morning, gets you focused on what you need to do.
“Unfortunately, it didn’t go my way, but the crowds have been amazing.”
Four-time major champion McIlroy won the Canadian Open in 2019 – the last time it was in Hamilton – and again in 2022 at St George’s in Toronto.
“One of the main reasons I love coming back here is because of that atmosphere,” McIlroy said.
“Playing with two Canadians today, it was exactly what I expected.”
Skinns, a former Canadian tour player, birdied the par-4 12th – hitting a wedge from 104 yards to four feet – and began his big run on the par-5 17th.
“The golf up here is pretty cool,” Skinns said.
“It’s one of the best-looking courses I’ve seen. Definitely, a joy to be back.”
Burns eagled the par-5 17th and 4th.
“With all the rain we had early in the week the greens are still pretty receptive,” he said.
“It makes a big difference on par-5s when you have a long iron or a wood coming in there to be able to stop the ball pretty quick.”
