Graduated from De La Salle (Calif.) High School...Committed to play at UCLA prior to being drafted...Played for 18U Team USA Baseball in 2019, winning a silver medal at the WBSC U18 Baseball World Cup in South Korea...His younger brother, Connor “Bear” Harrison, is a junior catcher at Texas A&M...His grandfather, Skip Guinn, pitched in the Major Leagues with Atlanta (1968) and Houston (1969 and 1971)…His mother, Kim Guinn, played field hockey at San Jose State University...Enjoys hiking, golf, traveling and cooking.
2025
Went 1-1 with a 4.04 ERA in 11 games (six starts) with San Francisco (eight G, four GS) and Boston (three G, two GS)...was traded by the Giants to the Red Sox on 6/15 as part of the deal that sent INF/DH Rafael Devers to San Francisco...Also went 5-2 with a 3.66 ERA in 18 starts between Triple-A Sacramento (six GS) and Triple-A Worcester (12 GS)...Was on the AL Wild Card Series roster against New York but did not pitch...Was traded by Boston to Milwaukee as part of a six-player deal on 2/9/26.
2024
Made his first career Opening Day roster...Was the youngest player on the Giants’ Opening Day roster...Entered the season as the Giants’ No. 1 prospect per MLB.com (No. 23 overall)...Went 7-7 with a 4.56 ERA and 118 strikeouts in 24 starts...The Giants were 14-10 in those starts...Worked a career-high 124.1 innings...In 2023, Harrison tossed 102.1 innings between Triple-A Sacramento and the Giants...Dating to 2023, Harrison struck out 66 batters over his first 13 big league games...Since 1901, only two other Giants lefties struck out 66+ batters through their first 13 games: LHP Shawn Estes (71) and LHP Andrew Suàrez (66) (Stats, LLC)...Was a stopper for the Giants, going 5-3 with a 3.62 ERA in starts following a Giants loss...Matched a career-best with 11 strikeouts on July 26 vs. Colorado...Became the first Giant with 11 strikeouts and one hit or fewer allowed in a game since LHP Madison Bumgarner vs. the D-Backs in 2016...Rolled his right ankle working out in the Giants’ gym on June 15 and was placed on the 15-day injured list the next day with a right ankle sprain...Missed 20 games before being activated on July 6...Was placed on the 15-day injured list with left shoulder inflammation on Sept. 6 and was shut down for the remainder of the season...Tossed a career-high seven shutout innings on May 7 at Colorado, becoming the sixth Giants pitcher to throw at least seven shutout innings at Coors Field, joining Barry Zito (4/9/12; 9.0 IP), Tim Lincecum (6/11/08; 7.0 IP), Matt Cain (4/17/07; 7.0 IP), Jason Schmidt (7/17/04; 8.0 IP) and Russ Ortiz (8/28/02; 8.0 IP).
2023
Started the year at Triple-A Sacramento and made 20 starts for the River Cats before having his contract selected. Went 1-3 with a 4.66 ERA (34er, 65.2ip) and struck out 105 of the 295 (35.6%) batters he faced at Triple-A...his 14.50 K/9ip in the minors ranked as the second-highest figure in all MiLB (min. 65.0ip). Had his contract selected on Aug. 22 and made his MLB debut that night at Philadelphia...at 22 years and 10 days old, the southpaw became the youngest Giant to make his first career start since Madison Bumgarner in 2009 (20 years, 38 days). He was also the first Giants pitcher to start in his MLB debut since RHP Logan Webb on Aug. 17, 2019 at Arizona...Made his first career appearance at Oracle Park on Aug. 28 vs. the Reds...threw 6.1 innings and was awarded his first career win...became the youngest Giant to earn a win since Bumgarner (Aug. 9, 2011 vs. PIT)...Harrison struck out the first five batters he faced and 11 of the 24 overall in the Aug. 28 start vs. Cincinnati...The start also made Harrison the youngest Giant (22 years, 16 days) to record 11 or more strikeouts in a game since Madison Bumgarner (21 years, 329 days) on June 26, 2011 vs. CLE (11) and the first Giants rookie overall to strike out at as many batters since Chris Heston’s no-hitter on June 9, 2015 at NYM. Became just the third rookie to record 11 or more strikeouts at Oracle Park...Harrison was just the second player in Giants history to have a double-digit strikeout game in their second-career start (other: Jeff Tesreau with 10 in 1912) and the first Giant since Randy Johnson (May 1, 2009 vs. COL) to start a game with five-straight strikeouts...Struck out 14 of the first 30 batters he faced in his MLB career, the third-most by a starter through as many batters since 1901, trailing only WSH’s Stephen Strasburg (17, 2010) and MIL’s Freddy Peralta (15, 2018)...he also became the only left-handed pitcher in the modern era to strike out 40% or more of the batters he faced through his first two starts (Opta- STATS)...Gave up eight home runs through his first six career starts...the homers were the most by a Giant in their first six career games in franchise history. Tossed 5.0 innings of no-hit ball in his last start of the year on Oct. 1 vs. the Dodgers...struck out five and walked three to become the first Giants rookie to exit with a no-hitter intact through 5.0 innings since Chris Heston threw his no-hitter on June 9, 2015...Harrison also became the third rookie in the SF era to accomplish that feat (also: Jim Barr on Sept. 11, 1971)...Suffered a moderate hamstring strain on July 5 while training in between starts...the injury led him to miss what would have been his second Futures Game...returned to play on July 31 and made four starts in the minors before having his contract selected on Aug. 22.
2022
Started the season with the High-A Eugene Emeralds and posted a 1.55 ERA (5er, 29.0ip) over seven games started...struck out 59 batters over his 29.0 innings of work... Was promoted to Double-A Richmond in late-May...at 20 years old when he debuted, Harrison became the youngest pitcher in the history of the franchise... Made 18 starts for Richmond, going 4-2 with a 3.11 ERA (29er, 84.0ip)...recorded 127 strikeouts, compared to just 39 walks allowed... Was named to the 2022 Futures Game and allowed two home runs in 0.2 of an inning.
2021
Spent the entire season at Single-A San Jose where he racked up 157 strikeouts in 98.2 innings over 23 starts pitching in his backyard...Named the California League’s Pitcher of the Year after his terrific season in San Jose...Harrison’s 157 strikeouts were tied for eighth-most in the minors..
