Glasnow attended
William S. Hart High School in
Santa Clarita, California. He committed to play
college baseball for the
University of Portland.
Pittsburgh Pirates (2011–2018) Minor leagues in 2015 The
Pittsburgh Pirates selected Glasnow in the fifth round (152nd overall) of the
2011 Major League Baseball draft. Glasnow signed with the Pirates for a $600,000
signing bonus. Glasnow made his professional debut in 2012 for the
Gulf Coast League Pirates of the
Rookie-level Gulf Coast League in 2012 where he went 0–3 with a 2.10 ERA in 11 games (ten starts), and also started one game for the
State College Spikes of the
Low-A New York–Penn League. In 2013, he played for the
West Virginia Power of the
Single-A South Atlantic League. Glasnow started 24 games and finished the season with 9–3 record, a 2.18 ERA and 164
strikeouts in 111.1 innings. His 164 strikeouts were the most in a single season in Power franchise history, surpassing
Will Inman's 134 in 2006. Glasnow played for the
Bradenton Marauders of the
High-A Florida State League in 2014. In 23 starts for Bradenton, he compiled a 12–5 record and 1.74 ERA. After two starts with West Virginia, Glasnow returned to Altoona. In late July, the Pirates promoted Glasnow to the
Indianapolis Indians of the
Triple-A International League. The Pirates considered promoting Glasnow to the major leagues in 2015, but decided against it. In 22 starts between the three clubs, Glasnow was 7–5 with a 2.39 ERA and 136 strikeouts in innings. He began the 2016 season with Indianapolis and had a 1.87 ERA and 133 strikeouts in innings pitched across 20 games started. He pitched innings in his major league debut, giving up four runs on three hits and two walks. Glasnow's first MLB strikeout was of
Aledmys Díaz of the
St. Louis Cardinals. In his second start, he left the game after three innings with a shoulder injury. Glasnow returned to the active roster in September as a
relief pitcher and did not start another game until September 25. In innings pitched for Pittsburgh in 2016, Glasnow was 0–2 with a 4.24 ERA and 24 strikeouts. In his first start of 2017, he struggled with his
command, giving up five runs on four hits and five walks in innings pitched. Glasnow was optioned to Indianapolis in June after compiling a 7.45 ERA and 1.91 WHIP over 12 starts. He spent the remainder of the season with Indianapolis, where he was 9–2 with a 1.93 ERA over 15 starts, before returning to Pittsburgh during September call-ups. In 15 games for the Pirates, he compiled a 2–7 record, a 7.69 ERA, and a 2.012
WHIP. During
spring training in 2018, the Pirates decided that Glasnow would start the 2018 season as a relief pitcher and he appeared in 34 games with a 4.34 ERA in 56 innings. He was immediately inserted into their
starting rotation. In his 11 starts with Tampa Bay, Glasnow posted an earned run average of 4.20, recording 64 strikeouts in innings. He strained his arm against the Yankees on May 10 which kept him on the injured list until September. He returned to make four starts, none of them lasting more than five innings. He finished the 2019 season with a 6–1 record and a 1.78 ERA in innings. In the
pandemic shortened 2020 season, Glasnow was 5–1 with a 4.08 ERA in 11 starts. and
Division Series (
Yankees). In Game 5 of the ALDS, he started the game on two days' rest. This was the second straight year Glasnow started the fifth game of the
ALDS for the Rays; both times he faced off against his former teammate
Gerrit Cole. Glasnow became the second pitcher since 1980 to start a game on two days' rest. He started two games of the
World Series against the
Los Angeles Dodgers, losing both games and allowing 10 earned runs in innings. Glasnow began the 2021 season by making 14 starts, with a 5–2 record and 2.66 ERA. After an unsuccessful attempt to rehab the injury, it was revealed that he needed
Tommy John surgery. This caused him to miss the rest of 2021 and most of 2022 as well. On August 22, 2022, the Rays and Glasnow agreed to a contract extension through the 2024 season, that would pay him $5.35 million in 2023 and $25 million in 2024. On September 28, he was activated off the injured list made his 2022 season debut against the
Cleveland Guardians that night, pitching three innings with three strikeouts while allowing one earned run. After one more regular season start, Glasnow was named the starting pitcher for the Rays in Game 2 of the
AL Wild Card Series between the Rays and the Guardians; he allowed two hits and recorded five strikeouts over five scoreless innings. On February 28, 2023, it was announced that Glasnow would miss the beginning of the 2023 season with a Grade 2 strain of his left oblique. He rejoined the rotation on May 27 and made 21 starts in 2023, with a 10–7 record and 3.53 ERA. He also started the first game of the
Wild Card Series against the
Texas Rangers, taking the loss while allowing three earned runs in five innings.
Los Angeles Dodgers (2024–present) On December 16, 2023, the Rays traded Glasnow and
Manuel Margot to the
Los Angeles Dodgers in exchange for
Ryan Pepiot and
Jonny DeLuca. Additionally, Glasnow agreed to a five-year contract extension for $136.5 million, which also included both club and player options for the 2028 season. Glasnow was selected to start for the Dodgers in the
MLB Seoul Series opener against the
San Diego Padres in
South Korea. On March 28, he picked up his first win as a Dodger against the
St. Louis Cardinals. On April 9, he threw seven scoreless innings and tied his career-high with 14 strikeouts against the
Minnesota Twins. He also became the first pitcher to strike out 14 or more batters in a game while throwing fewer than 90 pitches since they first tracked pitches in 1988. Glasnow was selected to his first All-Star game in 2024. He had career highs in starts (22), innings pitched (134) and strikeouts (168) while producing a 9–6 record and 3.49 ERA. Glasnow returned to Los Angeles' rotation to begin the 2025 season, posting a 1–0 record and 4.50 ERA with 23 strikeouts over his first five starts. He was placed on the injured list due to right shoulder inflammation on April 28, 2025, and was transferred to the 60-day injured list on May 31. He was activated from the injured list and rejoined the rotation on July 9 against the
Milwaukee Brewers. He made a total of 18 starts, with a 4–3 record, 3.19 ERA and 106 strikeouts. He started the decisive fourth game of the series, striking out eight while allowing only two hits and three walks in six scoreless innings of a game the Dodgers eventually won in extra innings. His next start was in the third game of the
2025 NLCS against the Brewers, allowing one run on three hits and three walks with eight strikeouts in innings as the Dodgers won on their way to a series sweep. Glasnow also started the third game of the
2025 World Series against the
Toronto Blue Jays. He allowed four runs (only two of which were earned) on five hits and three walks in innings of a game the Dodgers eventually won in 18 innings. He next came in to the ninth inning of Game 6 with two on and no outs and picked up his first career
save on only three pitches – a popout and a double play. The following day in Game 7, he allowed one run on three hits in innings in a game the Dodgers eventually won to take the series. ==International eligibility==