The Washington Capitals played the long game with Fehervary, a defenseman they selected in the second round (No. 46) of the 2018 NHL Draft. He played his first full season for HV71 of the Swedish Hockey League after signing a three-year, entry-level contract with the Capitals on July 1, 2018, a plan designed to get him ready for a move to North America and a development path similar to those of centers Nicklas Backstrom (No. 4, 2006 NHL Draft), Marcus Johansson (No. 24, 2009 NHL Draft) and Evgeny Kuznetsov (No. 26, 2010 NHL Draft) took on their way to the Capitals.

Fehervary attended his first NHL training camp before the 2019-20 season, after having moved to Sweden from his native Slovakia to live with a billet family when he was 14 and on his own since age 15. He played four games in the SHL as a 16-year-old with Malmo in 2015-16 and nine more in 2016-17, and 42 games for Oskarshamn in Sweden's second-highest league in 2017-18.

"It was a great experience, a life experience," Fehervary told NHL.com. "I think it helped me a lot in my social life too, and with hockey the most."

Fehervary made his NHL debut Oct. 2, 2019 and scored his first NHL point, an assist, Feb. 8, 2020, four days before the NHL paused the season due to concerns surrounding the coronavirus. He scored his first NHL goal in a 4-3 overtime loss to the Calgary Flames on Oct. 23, 2021.