The 21-year-old American will contest her first grand slam final on Saturday when she takes on two-time major winner Garbine Muguruza at Melbourne Park.
Kenin had never previously been beyond the fourth round at a slam but she showed her big-match mentality in beating Serena Williams at the French Open last year and has risen swiftly up the rankings to 15th.
She was also a child prodigy marked out for stardom at an early age, while she made her US Open debut at 16.
Kenin's doubles partner, Bethanie Mattek-Sands, said: "Everyone is surprised. But, knowing her and seeing some of her wins this year, I am not really surprised.
"I don't consider her that much of an outside shot at this title. She is feisty, she showed mentality really wins matches."
After ending the run of 15-year-old Coco Gauff in the fourth round, Kenin played the party pooper role again by knocking out big home hope Ashleigh Barty in the semi-finals.
"I watched the match yesterday and the feeling was Ash had a lot of momentum in both sets and it really was Sofia's fire that got her through," said Mattek-Sands.
"She came up big with some returns on the right points and that's what it takes. Her ball is deceptively big. She places it well and she just does what it takes.
"If it takes doing a two-handed backhand drop shot, if it takes lobbing all day long, she goes in with the mentality, 'What have I got to do to win?' And that's what champions do.
"I'm proud of her. She's just a really a unique person who is genuinely herself and I think that's ultimately what wins tennis matches."
Kenin will break into the top 10 on Monday no matter what the outcome and would climb to seventh with victory.
Given her competitive nature and cool head so far, it would be a surprise if she did not handle the occasion with aplomb.
"I'm just going to be enjoying the moment," she said. "You don't experience this so often. This is so exciting. Literally butterflies.
"I'm just going to also focus on what I need to do, focus on my game. I got here, it's time to shine, do the best I can – hopefully do something more special."
Muguruza's off-season included a very different physical challenge, the 26-year-old eschewing the usual tennis player's beach holiday to climb Mount Kilimanjaro, the highest mountain in Africa.
While Muguruza was reluctant to link the two achievements, Martinez sees parallels.
"Her stories, it's super cold where you can barely rest and you have to continue walking, where you had to overcome your fears and also be strong to continue, I think that gives you something mentally, that's for sure," said the 47-year-old.
"She was stubborn enough to get there and she did it. I think that gives you something on the court where you might see something that is impossible, but everything is possible if you have the right mentality. She has the right mentality."