Skating to Vivaldi's "Four Seasons," the 20-year-old was nearly flawless, snapping out a clean set of jumps including a quad toeloop and triple toeloop sequence that drew cheers from the crowd for a whopping 103.25 points.
He wobbled on his initial quad flip but was able to hold on, which he said was "a relief."
"It wasn't a perfect performance, but I thought it was pretty good overall," he said. "I thought I might fall on the flip, but I managed not to, so that gave me confidence." Israel's Alexei Bychenko racked up a season's best of 88.49 to finish second with his skate to "Hava Nagila," a Jewish folk song.
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But falls marred the performances of Canadian veteran Patrick Chan and the U.S.'s Nathan Chen, 18, who is making his Olympics debut.
The 27-year-old Chan, who won silver in the individual and team events at Sochi in 2014, struggled with his jumps, taking a tumble on his opening quad toeloop and his triple Axel. He earned 81.66 points to finish third.
"It was not the best but this is the advantage of a team event - it's what we can each contribute," Chan told reporters. "If anything, I think I was too eager on the jumps."
American Chen hung on to land his opening quad flip but went on to double his quad toeloop and make an uncharacteristic fall on his triple Axel, earning him 80.61 points and leaving him in fourth.
"I just wasn't thinking about the right thing technically. I was ahead of myself in terms of how to land a jump, how to get out," he said.
"I think that it was a good opportunity for me to put myself out there and make silly mistakes like this. In individual, I'll be more ready.
"No one wants to skate like that on Olympic ice. But it happens. Just take it and move on."
Uno said he was surprised by the number of mistakes by the others and said the early start time might have contributed. Skating events normally take place in the afternoon or evening.
"Skaters who are usually so stable really fell a lot," he said. "I thought it was because it was early morning and there were nerves because of the Olympics.
"I also thought I'd mess up, I was worried, and just thought that I'd fail too. I was really relieved after the first jump."
The countries' pairs for the team event are set to skate their short programmes later on Friday, while the short programmes for the women's and ice dancers take place at the weekend.