Clayton showed off his snapping jab and quick hands in a four-round light middleweight victory over Frenchman Sophyan Haoud on Friday night at the Pepsi Colisee.
Two judges gave him all four rounds while the third scored it 39-37, with Haoud having his best moments in the third.
The bout was on the undercard of Canadian Adonis Stevenson's fourth defence of his WBC light heavyweight title later Friday against Russian Dmitry Sukhotsky.
Normally, boxers in their first pro fight are given easy opponents, but Haoud (3-3-1) showed he could take a punch and was on attack from the opening bell.
"We didn't want to pick one that was too easy," said Clayton, a six-time Canadian amateur champ who reached the quarter-finals at the 2012 Olympics in London. "I've been around for a while, and with my experience, I figured a nice tough fight for my first one would be good.
"He was a good fighter. Very tough."
Clayton connected with a clean left hook early in the first and had Haoud in trouble late in the round. But the French fighter managed to hold off a late flurry of punches to survive the round.
"I saw I hurt him, but he was tougher than I thought. He took the shot," said Clayton.
Promoter Yvon Michel, who signed Clayton to a three-year contract in November, feels he was Canada's best amateur since Stevenson.
He liked his debut, but said nervousness may have prevented Clayton from showing his best against Haoud.
"It reminded me a little of (former light heavyweight world champion) Jean Pascal," said Michel. "His first fight, he was also nervous. That's why he wasn't quite as sharp as I believe he would have preferred to be.
"But it's good. The ice is broken now and we're looking for good things in the future."
Michel hopes to fast-track 27-year-old Clayton to be a top contender within 18 months and to fight for a world title within three years.
Quebec commission rules mandated that his first fight be only four rounds, but Michel said he will jump up to a six-rounder in his next bout.
"He has good combinations, good speed, imagination," said Michel. "The only thing was, just because he was nervous, he wasn't able to snap his punches like he's used to, like I've seen in the gym. But that was expected."