Keeping up with the new besties in the Kardashian-Jenner entertainment complex can be a full-time job.

But even in their social media panopticon, Sophia Hutchins stands apart, and not just because of her ice-goddess looks and self-promotional savvy. Sometime in 2017, tabloid stories began linking Ms. Hutchins to Caitlyn Jenner, first as “friends” and “gal pals” who shopped and vacationed together.

Before long, the tabloids said that the two were romantically involved, and often pointed out their age difference: Ms. Jenner, who is 70, was apparently dating someone younger than her 24-year-old daughter, Kendall. (Ms. Hutchins is 23.) Some reports went so far as to say they were engaged.

“Who is Caitlyn Jenner’s fiancée Sophia Hutchins?” read a headline in The Daily Mirror in 2018. ”

Ms. Hutchins has not exactly hurried to dispel those rumors. She has posted selfies on Instagram from what looks like Ms. Jenner’s bed, with the caption “home sweet home.” Another time, she created an Instagram Story and took questions from followers; when one asked, “Are you in a relationship?,” she replied coyly, “Oh yes!” without naming anyone.

But Ms. Hutchins, the C.E.O. of a start-up beauty brand, has never commented directly on their relationship, until now.

On a recent Monday afternoon, Ms. Hutchins was sipping green tea in the lobby of the Mercer hotel in the SoHo neighborhood of Manhattan. Dressed in a black Alice + Olivia turtleneck, she had straight blond hair that framed her slate-blue eyes and gravity-defying cheekbones. She bore an uncanny resemblance to Ivanka Trump.

Ms. Hutchins grinned at the comparison to the first daughter. “I’ll take it,” she said, adding that she is not a registered Republican. “I think Ivanka is gorgeous.”

Seated with perfect posture, Ms. Hutchins expressed emotion sparingly and came across as analytical and preternaturally poised. She was keen to discuss her beauty product, Lumasol, a sunscreen mist she plans to release next year. We would get to that.

But first: Are she and Ms. Jenner really a couple?

Ms. Hutchins folded her hands on the table, set her blue eyes to stun and said in a matter-of-fact manner: “We were never romantically involved.”

So why have the tabloid reports persisted? “Because we weren’t addressing it,” she said. “I don’t feel a need to address my sex life, quite frankly, unless I want to.”

She took a sip of tea and, with her firm tone, indicated that the matter was closed.

Class President to Celebrity Manager

Before the spotlight beckoned, Ms. Hutchins grew up in Seattle, where she was a three-time state high school debate champion. She was raised by a single mother, who worked as a dental hygienist, and her grandparents.

“My grandfather, a rocket engineer at Boeing, was the greatest influence in my life,” she said. “My grandparents stepped in and helped out by sending me to an elite college prep school,” and later to Pepperdine University in Malibu, Calif., in part because it offered the best financial aid package.

Slightly built and studious, Ms. Hutchins initially identified as a gay man. At college, she was active in student government and planned a career in finance. But in 2016, during her junior year, she announced on Facebook without explanation that she was resigning as the student class president.

A few weeks later, she gave an interview to the Graphic, a Pepperdine student newspaper, explaining that she was taking a semester off to transition. “I’ve always had the question of ‘Do I want to transition from male to female?’” Ms. Hutchins was quoted as saying. “I never thought a lot about doing it until I got into college because I was able to break away from my family and started to establish my own identity.”

She regrets the interview, saying that she feels overly defined by her gender transition. “Had I not done that interview, I never would have come out,” she said. “I would just live my life. Now people can’t really see past the trans thing.”

She also told the newspaper that two things inspired her to transition: the support of her friends and family, and seeing Ms. Jenner talk about her journey on “20/20.”

Ms. Hutchins would soon meet her inspiration. After returning to college, she embraced a newly invigorated social life and popularity. “I blended right back in on my first day back,” she said. “The guys were like, ‘Did you transfer in? I’ve never seen you before.’”

Her new lifestyle also included a hair-and-makeup team. (Asked why a college student would hire personal grooming stylists, a spokeswoman for Ms. Hutchins, Kristen Shea, said: “In L.A., regardless of whether you are a student, most everyone has hair and makeup people. I mean, glam squads are almost a given.”)

One member of her glam squad was working with Ms. Jenner and thought the two would hit it off. “We were introduced through my makeup artist at a M.A.C. photo shoot,” Ms. Hutchins said. “Having a similar sense of humor, we spent the entire time laughing and ended up meeting for brunch, and we’ve been great friends ever since.”

Ms. Hutchins, who had become disillusioned with a career in finance, also sensed an opportunity. Ms. Jenner’s former wife, Kris Jenner, was no longer her business manager. And although Ms. Hutchins had no relevant experience, she was persuasive and ambitious enough to convince Ms. Jenner to hire her.

“I saw nobody was managing her, and there were all these people taking massive advantage,” Ms. Hutchins said. “And I was saying, ‘Caitlyn, if I don’t step in here and start managing you, you’re going to go broke.’”

They quickly developed a level of trust and, during her senior year, Ms. Hutchins became Ms. Jenner’s manager, taking a 10 percent cut. She also moved into Ms. Jenner’s ridge-top home in Malibu, the same four-bedroom, 11-acre compound where the “20/20” interview took place.

Since signing on, Ms. Hutchins said she has taken the lead on negotiating a raft of deals, including paid speeches for T-Mobile and the Harvard Leadership Summit, and before Britain’s House of Commons for Channel 4.

She also negotiated Ms. Jenner’s recent appearance on “‘I’m a Celebrity … Get me Out of Here,’” a reality show in Britain, “which has been reported to be the highest fee in the show’s history,” Ms. Hutchins said. “We made a lot of money together and still do.”

Approached for comment, Ms. Jenner declined to be interviewed, but her publicist emailed a statement: “Over the last few years, Sophia has been my best friend, family and confidant. She is one of the top minds in her field. Her value in my life is undeniable. The sky is the limit with her entrepreneurial spirit.”

Her ‘Extended Family’

It didn’t take long for Ms. Hutchins’s business radar to detect other opportunities. The idea for her beauty product, Lumasol, was born one night in 2017 over dinner with Jami Morse Heidegger, a neighbor in Malibu who is an heir to the Kiehl’s beauty brand.

“We were talking about what’s missing in the market and I said, ‘Why can’t I get a makeup-setting mist with SPF?’” she said, referring to a spray used to help makeup last.

After months of market research, testing and pitch meetings, Lumasol is scheduled to begin selling next April. The mist will be priced between $30 and $50 and will be packaged in a bottle that changes color when exposed to ultraviolet rays, nudging consumers to spray early and often.

“We consider ourselves a health tech company because we see SPF as the first entry point to tackling the health crisis which is skin cancer,” Ms. Hutchins said.

Being associated with the Jenner-Kardashian clan probably doesn’t hurt. “I’m on good terms with all the family, but I’m closest with Kris, Kim, Kylie and Kendall,” said Ms. Hutchins, who recently posted a picture of herself to her 100,000 Instagram followers from a family dinner for Ms. Jenner’s birthday, standing between Kim and Kourtney Kardashian.

“And anytime I needed a meeting with someone that I couldn’t get, Caitlyn could get it for me,” she added.

She has raised $3 million in seed funding, including from Greycroft, a venture firm in New York. “If you attach an influencer with a huge following to a consumer product, it’s like having your own media channel,” Ian Sigalow, a founder of Greycroft said in an interview with Forbes this year. “Lumasol’s starting on third base — they’re going to take off.”

But Ms. Hutchins is not counting on free promotion from the women she calls her “extended family.” “If I want someone in that clan to promote the product, they’re going to be compensated,” she said. “And these girls are not cheap.”

Ms. Hutchins set down her tea and checked the time; she was fitting the interview into a busy day of meetings. When her phone rang, she didn’t hesitate to pick up. It was Ms. Jenner calling to report on repairs to her private plane, a Beechcraft Baron turboprop.

“I need to get to San Francisco from L.A. on Thursday super-early, and Caitlyn is flying me,” Ms. Hutchins said.

Hearing from Ms. Jenner seemed to cheer her up. The call also provided an opening to return to more personal questions. If she is not dating Ms. Jenner, is there another special someone?

Turns out, there is. Ms. Hutchins confided that she just started dating a 30-year-old gentleman who graduated from Harvard and works on Wall Street. No other details would be forthcoming. But for the second time that afternoon, she softened her gaze, looked up and smiled.