Harrison Browne made headlines last October after he came out publicly as a transgender professional athlete.

Now, he's retiring from women's hockey — but not before going out as a champion.

On Sunday, the 23-year-old forward helped his team win the the National Women's Hockey League (NWHL) championship trophy, the Isobel Cup. The Buffalo Beauts downed the Boston Pride 3-2 in a stunning upset.

2017 ISOBEL CUP CHAMPIONS! <a href="https://t.co/kunJcPJSs5">pic.twitter.com/kunJcPJSs5</a> —@BuffaloBeauts

The Oakville, Ont. native released a YouTube video recently detailing his decision to retire. Browne said ultimately, he needed to start focusing on his career off the ice — something he didn't want to do as a woman.

"Transitioning definitely is a big deal for me," he said in the video. "I just simply can't really go on. I get misgendered all the time, and that's not something I want in this stage in my life."

The NWHL announced a transgender policy in December, which outlined the league's support for players who choose to express their gender beyond the binary of female and male. However, the rules bar athletes transitioning from female to male from taking testosterone hormone therapy.

"I feel that I've given myself as much as I can to my sport," Browne said. "I hope maybe I can pass the torch down to somebody who needs it, and somebody who can be brave and take the reins on this."

Browne said a lot of thought went into his difficult decision to retire from the sport he loves. He didn't want to disappoint anyone who may think of the choice as "giving up."

"I've played hockey for 15 years and I've made a huge career out of it," he said. "I did not give up on it. I milked it for as long as I could."

He said he went back and forth until someone told him it was time to focus on himself.

Harrison Browne teared up when asked about becoming the first trans athlete to win a professional team championship. Emotional moment. <a href="https://t.co/c7pmQh0jRX">pic.twitter.com/c7pmQh0jRX</a> —@Hannah_Bevis1

Browne first approached the league about a name and gender change in the summer. He said it just didn't feel right to score a goal and hear the announcer call out, "Hailey Browne!"

Trailblazing in the NWHL was a first step, of sorts. Now, he's beginning the process of transitioning to male.

Buffalo Beauts forward Harrison Browne is retiring to complete his transition from female to male. (Michael P. Majewski/NWHL via AP)

Browne will be pursuing a career in sports business, but he will continue to stay active in the NWHL. He will serve on the league's board of advisers, lending his experience on inclusion.

He said he will also continue to be a trans advocate.

As for his future as a hockey player, that's still up in the air.

"Who knows — I may play on the men's side," Browne said. "I'm not ruling that out, but I'll take it as it comes."