Australia’s David Morris sprung a surprise in the super final to take silver, while Jia Zongyang of China took bronze to edge his compatriot and reigning world champion Qi Guangpu off the podium.
Following Alla Tsuper's victory in the women's competition three days earlier, Kushnir took on the mantle for Belarus in the final of the men’s event, after his compatriot Alexei Grishin, the Vancouver 2010 champion, was eliminated in the heats.
Kushnir, competing at his third Winter Games and chasing his first ever medal, managed a staggering score of 134.50, thanks to a successful double-full-full-double-full jump, involving three flips and five twists.
Meanwhile, his two main Chinese rivals botched their landings after attempting complicated jumps in the super final, and recorded sub-100 scores.
“I was just lucky today to be honest,” said a modest Kushnir. “I like to jump when my competitors are at a high level, it stimulates me.
“Unfortunately, the Chinese athletes made mistakes. I thought it would be close and decided on small technical issues but they made mistakes,” he added.
Meanwhile, Morris, who posted a relatively modest score of 110.41 points, could not disguise his own surprise at finding himself on an Olympic podium.
“To be honest, I'd never been to a super final before so I thought: ‘I've never been here, I've got as far as I can possibly get, I'd be happy with a fourth’,” he said.
“I don't expect to beat some of these guys with their huge jumps, so I didn't feel I was under pressure to win,” he added.
Jia said he had no regrets about trying such a tough jump in the super final. “If I didn't try this jump maybe it would have been a safer plan but I would have regretted it,” he said.
The Chinese pair had dominated the previous three rounds, with either Jia or Qi recording the top score, but neither could reproduce their best at the crucial moment.
Earlier in the day, the defending champion Grishin had been knocked out after finishing second last in the first heat and then failing to make a top six finish in the “second-chance” heat.