Sundling won all her heats and stormed to a stunning victory in the final ahead of compatriot Maja Dahlqvist, with Jessie Diggins of the United States holding off fellow American Rosie Brennan to pick up the bronze.
Wearing bib No. 1, Sundling crushed everyone in her path, taking victory in the final by a margin of 2.88 seconds ahead of Dahlqvist in a sport where athletes often lunge over the line to win by milliseconds.
"It’s crazy, I probably haven’t really understood it yet," Sundling said.
"I never felt completely sure. There were so many on the starting line who are so good. It’s high elevation and a tough course and even if it feels good, you never know until it’s over. But I handled all the races well, never exceeded my limits and could keep a high pace throughout.”
Diggins, who helped break an American cross-country medal drought dating back to 1976 with her team sprint victory in 2018 alongside Kikkan Randall, dug deep again with a typically gutsy, come-from-behind performance.
"It feels amazing, it belongs to the whole team,” Diggins said. "We have come a long way as a country and it is very special to have it all come together."
Klaebo made the most of the absence of recently-crowned skiathlon champion Alexander Bolshunov to grab his first gold of the Games, with Italian Federico Pellegrino taking silver and Alexander Terentev claiming the bronze for the Russian Olympic Committee.
Klaebo was out for vindication after a poor performance in the skiathlon race on Sunday and he got it in the final, bursting out of the gate and holding off the early challenge of young Swede Oskar Svensson.
The rest of the six-man field could not match his power on the uphill climbs and he crossed the line 0.26 seconds ahead of Pellegrino, whose semifinal lunge had given him an unlikely berth in the final.
"It's a special one for sure," Klaebo said. "The last couple of weeks has been quite stressful. We had some COVID in the team and my coach is at home."
"There has been pressure for sure, trying to see if you can do it one more time. But having this amazing fight together today was special and it was a lot of fun."
Norwegian team coach Eirik Myhr Nosum said Klaebo was unique: “He has the ability to adjust, reading the course, the track and conditions."