Washington Nationals After signing, Klobosits began his professional career with the rookie-level
Gulf Coast League Nationals. He was promoted to the
Auburn Doubledays in July and then to the
Hagerstown Suns in August. In relief innings pitched between the three clubs, he was 1–0 with a 1.47 ERA and 1.01 WHIP. With an imposing physical profile at and , He was one of several pitching prospects the Nationals brought up for a simulated game to prepare their major league hitters for the
2017 National League Division Series. Klobosits underwent
Tommy John surgery in May 2018 after posting eleven appearances out of the bullpen for the
Potomac Nationals. He split the 2019 season between the GCL, Potomac, Hagerstown, going a combined 0–0 with a 2.03 ERA over innings. He did not play in 2020 due to the cancellation of the
Minor League Baseball season due to the
COVID-19 pandemic. Klobosits opened the 2021 season with the
Harrisburg Senators and the
Rochester Red Wings. On July 30, 2021, Washington selected his contract and promoted him to the active roster. He made his MLB debut that night in relief.
Oakland Athletics On April 11, 2022, the
Oakland Athletics claimed Klobosits off of
waivers. He appeared in 11 games for the Triple-A
Las Vegas Aviators, struggling to a 7.59 ERA with 12 strikeouts in innings pitched. Klobosits was designated for assignment by Oakland on June 8, following the promotion of
Jared Koenig. He was released the same day.
Gastonia Honey Hunters On July 5, 2023, Klobosits signed with the
Gastonia Honey Hunters of the
Atlantic League of Professional Baseball. In eight appearances out of the
bullpen, Klobosits registered a 1.13 ERA with seven strikeouts and one save across eight innings of work.
Toronto Blue Jays On July 22, 2023, Klobosits signed a minor league contract with the
Toronto Blue Jays organization. In 14 games for the Triple–A
Buffalo Bisons, he logged a 4.74 ERA with 12 strikeouts across 19 innings pitched. Klobosits elected free agency following the season on November 6.
Gastonia Ghost Peppers On April 24, 2024, Klobosits signed with the
Gastonia Ghost Peppers of the
Atlantic League of Professional Baseball. In 45 appearances for Gastonia, he logged a 5–5 record and 2.18 ERA with 46 strikeouts and 11 saves across innings of relief. Klobosits became a free agent following the season.
Cleburne Railroaders On April 21, 2025, Klobosits signed with the
Cleburne Railroaders of the
American Association of Professional Baseball. In three starts for Cleburne, he recorded a 3.18 ERA with 12 strikeouts across innings pitched. Klobosits was released by the Railroaders on June 20.
High Point Rockers On July 15, 2025, Klobosits signed with the
High Point Rockers of the
Atlantic League of Professional Baseball. In 13 appearances (one start) for the Rockets, Klobosits compiled a 3-0 record and 1.64 ERA with 28 strikeouts and one save over 22 innings of work.
Chicago Cubs On January 26, 2026, Klobosits signed a minor league contract with the
Chicago Cubs. ==References==