He has previously played in MLB for the Washington Nationals and Chicago White Sox and in the KBO League for the NC Dinos.

Fedde was considered a top prospect for the 2014 Major League Baseball draft,[7][8] and the Nationals selected him in the first round, 18th overall.

[11] During the Nationals' 2017 season, with the team struggling with its bullpen during the first half, Fedde was temporarily moved to a relief role.

[13] The move proved fortuitous for the Nationals, who lost Joe Ross from their rotation in July after he tore his UCL and saw veteran starter Stephen Strasburg lose time due to a nerve impingement in his throwing arm.

On November 18, 2022, the Nationals did not tender a contract offer for the 2023 season to Fedde, making him a free agent.

He won the pitching Triple Crown in turn, and became the first foreign pitcher to log 20 wins and 200+ strikeouts in a season.

[26] In 21 starts for the White Sox in 2024, Fedde compiled a 7–4 record and 3.11 ERA with 108 strikeouts across 121+2⁄3 innings pitched.

[27] On July 29, 2024, the White Sox traded Fedde to the St. Louis Cardinals as part of a three-team deal that also sent Tommy Pham and a player to be named later to St. Louis, sent Tommy Edman, Michael Kopech, and Oliver Gonzalez to the Los Angeles Dodgers, and sent Miguel Vargas, Alexander Albertus, Jeral Pérez and a player to be named later to the White Sox.