Seventeen-year-old Kim snatched a stunning gold medal in the women's halfpipe snowboarding, while Hirscher's long hunt for an Olympic title finally ended.
In the first doping case of the 2018 Games, 21-year-old short-track speed skater Kei Saito became the only Japanese ever to test positive at a Winter Olympics.
Austrian star Hirscher bagged an emotional Olympic gold at the age of 28 when he produced a brilliant slalom run to storm to a victory in the men's alpine combined.
But one prize had always eluded him -- an Olympic gold medal. His previous best was a slalom silver from Sochi four years ago.
After playing down his chances ahead of the race at blustery freezing Pyeongchang, this time he nailed it.
Making the best of a downhill run shortened because of blustery winds, he laid the foundations for victory.
Then he turned round and ran away with victory thanks to a stunning performance in his own speciality, the slalom.
After the race Hirscher said his career was complete.
"All the people expected me to win a gold medal, especially in Austria, my home country, where skiing is big," he said.
"Everyone is saying, 'Nice career, but an Olympic gold medal is still missing'. This is perfect, unbelievable."
For Chloe Kim, her debut Olympics turned golden as she romped to snowboarding halfpipe victory. Born in the United States to Korean parents, Kim burst into tears as the enormity of her achievement sunk in.
The teenager, who has melted the hearts of home fans in Pyeongchang thanks to her ever-ready smile and Korean heritage, justified her status as the hot favourite with an eye-popping top score of 98.25.
- 'This one's for Grams!' -
Pumping her fists after finishing with back-to-back 1080 spins, Kim was serenaded by a pumped-up crowd chanting: "Chloe Kim, Chloe Kim!"
"I'm a little overwhelmed," she said, after composing herself.
Kim also revealed that her number one fan -- her Seoul-based grandmother -- had been in the crowd cheering her on.
"I actually only found out my grandma was at the bottom before my second run," she said.
"So I thought 'this one's for Grams!'"
Meanwhile Japan's Kei Saito checked out of the athletes' village and vowed to clear his name after testing positive for acetazolamide, an unauthorised diuretic which can be used to mask performance-enhancing drugs.
"I want to fight to prove my innocence because I don't remember (taking the drug) and it's incomprehensible," Saito said in a statement.
Saito, a human biology student whose sister Hitomi is also competing in Pyeongchang, arrived at the athletes village on February 4.
He was woken up at 2:00 am the following morning by doping testers who took two samples. Both samples tested positive.
Saito was summoned before a CAS tribunal on Monday and suspended from the Games pending a full investigation.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)