Mlodzinski was selected by the
Pittsburgh Pirates with the 31st overall pick of the draft. He signed with the Pirates on July 2, 2020, for a $2.05 million bonus. He did not play a minor league game in 2020 due to the cancellation of the minor league season caused by the pandemic. Mlodzinski made his professional debut in 2021 with the
Greensboro Grasshoppers of the
High-A East. He was placed on the
injured list on July 12 with a shoulder injury, and was activated on August 14. He returned to the injured list once again on September 9, but was activated only one week later. Over 14 starts with Greensboro, Mlodzinski went 2–3 with a 3.93 ERA and 64 strikeouts over innings. Following the end of Greensboro's season, he was promoted to the
Indianapolis Indians of the
Triple-A East, with whom he pitched two innings. He was selected to play in the
Arizona Fall League for the
Peoria Javelinas after the season. He was assigned to the
Altoona Curve of the
Double-A Eastern League for the 2022 season. In early May, he was placed on the injured list due to a shoulder injury but was activated a week later. Over 27 games (22 starts), he went 6–8 with a 4.78 ERA and 111 strikeouts over innings. To open the 2023 season, Mlodzinski was assigned to the
Indianapolis Indians of the
Triple-A International League. On June 16, 2023, Mlodzinski was selected to the
40-man roster and promoted to the major leagues for the first time after
Rob Zastryzny was placed on the injured list. At the time of his promotion, he had pitched 19 games for Indianapolis and registered a 3.16 ERA with 31 strikeouts and one
save in innings pitched. Mlodzinski played the remainder of the season with the Pirates, but was placed on the injured list with elbow soreness, and made one rehab appearance with Indianapolis. Over 35 appearances for Pittsburgh, Mlodzinski went 3-3 with a 2.25 ERA and 34 strikeouts over 32 innings. Mlodzinski opened the 2024 season on the injured list with right elbow inflammation. He was activated in April and optioned to Indianapolis. In May, the Pirates promoted him back to the major leagues. He was placed on the injured list on July 30 and activated on August 27. For the Pirates in 2024, Mlodzinski posted a 5–5 record and a 3.38 ERA with 46 strikeouts in 50 innings. Mlodzinski opened the 2025 season as Pittsburgh's fifth starter. He posted a 1-4 record and 5.67 ERA over nine starts before he was optioned to Indianapolis on May 21. The Pirates recalled him to the major leagues on June 11 and moved him back into the bullpen. Mlodzinski made a total of 34 appearances (12 starts) for Pittsburgh during the 2025 season and went 5-8 with a 3.55 ERA and 89 strikeouts across 99 innings. ==References==