London 2012 Olympic champion Le Clos made history by becoming the first man to win three consecutive 200m butterfly Commonwealth titles.
England's Peaty, meanwhile, retained his 100m breaststroke title, though not with the ease many would have predicted for a man who set a Games record of 58.59 seconds in Friday's semifinal.
The Olympic champion touched home in 58.84 seconds at the Gold Coast aquatics center, with his compatriot James Wilby (59.43) taking silver and South Africa's Cameron van der Burgh (59.44) bronze.
It was four years ago, at the Commonwealth Games in Glasgow, where Peaty made his major breakthrough and the Englishman has had no equal since.
The 23-year-old has not been beaten in the 100m breaststroke since Glasgow 2014 and in that time has amassed 26 medals, including 17 breaststroke golds.
Peaty's times are the fastest 11 over the distance in history.
"Even though it's a gold medal and it's four years undefeated and that's completed the circle, I'm not happy with that performance," Peaty, who will return to the pool Sunday for the 50m breaststroke, told reporters.
"It's not the best version of me. I want to go out there on the 50 and try to get that better version."
The world record holder added: "That's the first time ever where I've felt not in control of my race.
"I think I let the event get to me too much and I was thinking about the end result instead of the process.
"It's been a big learning curve here. My stroke feels nowhere near what it should feel like."
Le Clos wins 14th Commonwealth medal
Los Clos broke a Games record in winning gold, finishing in 1:54.00.
Australia's David Morgan (1:56.36) claimed silver, while Scotland's Duncan Scott (1:56.60) took bronze, adding to the bronze medals he won in the 200m freestyle and 4x100m freestyle relay.
Prior to the Games, Le Clos was bidding to equal a Games record of 18 medals, but failure to finish in the top three in the 200m freestyle and the men's 4x100m relay has ruined his hopes of becoming the most successful athlete in Commonwealth Games history.
His 200m butterfly gold was his second gold of these Games, however. On Friday he powered to victory in the 50m butterfly for the 13th Commonwealth Games medal of his career.
Games record for Campbell
There was a standing ovation for home favorite Cate Campbell as the Australian set a Commonwealth Games record of 23.78 seconds in winning the 50m freestyle.
Campbell's sister, Bronte, and Canada's Taylor Ruck both claimed silver after they both timed in at 24.26.
Sophie Pascoe, New Zealand flag bearer and the reigning Olympic champion, retained her title in the women's SM10 200m individual medley.
Canada's Kylie Masse also broke a Games record, clocking 58.63 seconds to win the women's 100m breaststroke.
She finished ahead of Australia's Emily Seebohm (58.66) in silver and Canada's Taylor Ruck (58.97) in bronze.
Elsewhere, Tatjana Schoenmaker won gold in the women's 200m breaststroke final to secure South Africa's second gold of the night, while Australia's Timonthy Disken came home first in the men's SB8 100m breaststroke final.
The Commonwealth Games run until April 15.