This year’s Super Bowl was many things to Kristin Juszczyk.

It was a crushing loss for her husband’s team, the San Francisco 49ers. But it was also the culmination of weeks of frenzied interest in the clothes she made by hand and wore to N.F.L. games. (The Super Bowl happened to take place on her 30th birthday, too.)

“This really all started as a hobby for me,” said Ms. Juszczyk, whose hobby — repurposing vintage team gear into one-off pieces — eventually made global headlines.

From early January to mid-February (or the N.F.L. playoff season, roughly), her Instagram following grew by one million people. Taylor Swift and Simone Biles wore puffer jackets designed by Ms. Juszczyk while supporting their football-playing partners. (Her husband is Kyle Juszczyk, a 49ers fullback.) She signed a licensing deal with the N.F.L., which allowed her to use the league’s logos on her clothing.

Ms. Juszczyk has spent the ensuing months figuring out how to scale her business so that she’s not just taking commissions from fellow WAGs and famous fans — her “bread and butter,” she said — but also making things that any fan can buy and wear.

She has also expanded into other sports; she designed a vest for the basketball player Caitlin Clark, for example. This weekend, the winner of the Indy 500 will be given one of Ms. Juszczyk’s jackets. So will the Indy 500’s national anthem singer, Jordin Sparks.

Ms. Juszczyk designed the Indy 500 jackets using vintage sweatshirts, T-shirts and checkered racing flags.

“When I think of Indy 500, I think of a very loud design,” said Ms. Juszczyk, who isn’t able to attend this year’s race — one of the largest sporting events in the world.

Here, in an interview edited and condensed for clarity, Ms. Juszczyk offers an update on her design career.

Talk to me about how you see yourself right now as a small-business owner. How do you feel expanding into a different sporting world?

My goal has always been to supply my designs to fans of all different events. I never wanted to pigeonhole myself to just the N.F.L., because I think there are fans in all sporting worlds and leagues and clubs that are looking for more fresh, fashion-forward designs.

I just have my head down, trying to get this business off the ground and get designs into fans’ hands. This is the first time I’m entering a licensed world, and I’m learning new things every day.

What do you think it is about your work that resonates with people?

As a designer, if you’re not wearing your own designs, then who’s wearing them? I’m a fan through and through. I go to every one of my husband’s games, and I realized about five years into his career that I didn’t want to wear the same four things in rotation. I wanted to push the needle and wear designs you couldn’t find anywhere else.

When did you make your first jacket?

I started sewing only about five years ago. One Halloween, I wanted us to be Justin and Britney from the AMAs — the full denim outfits. I couldn’t find them online, so I bought a bunch of old denim pants and started cutting them up. I bought a sewing machine and went on YouTube and learned how to use it. It came naturally to me.

Later, I decided to make a pair of sweatpants to wear to one of Kyle’s games, and it snowballed from there. I kept challenging myself to learn how to make shirts and skirts and blazers. This whole thing went crazy when I made the puffer vest and the puffer jackets — that’s what got the world’s attention. But it all started with a Halloween costume.

In your posts online, you make a point of showing the work that goes into these pieces.

I think it’s cool for people to see that I don’t have a fancy studio. I’m sewing on my Ping-Pong table. That’s another reason this resonates with people: It’s very relatable. People do projects at home all the time.

How did you approach designing this Indy 500 jacket?

I’m always trying to broaden my skill set. I’ve never made a bomber design this way, but I wanted it to feel more “racecar.” I kind of got into a rut making puffers.

I threw in a little Easter egg: There was a very famous moment in 1985, with Danny Sullivan, called the “spin and win.” If you look at the jacket, you can see that the flag is spun.

I’m excited to see who the winner is. There is a female racer this year, Katherine Legge. We’re rooting for everyone, but it would be really cool to see her win that jacket.