DeGrom began playing baseball as a shortstop and was converted into a pitcher during his junior year at Stetson University.

[6] As a senior baseball player the Florida Sports Writers Association named deGrom to the All-Florida second team.

[8] After not being selected in the Major League Baseball draft out of high school,[9] deGrom enrolled at Stetson and played for the Hatters.

Though he was considered a good fielder with a strong throwing arm, deGrom was a light hitter with a career .263 batting average.

[8] When deGrom returned to Stetson that fall, the team used him as a relief pitcher, filling the role of their closer, in addition to playing shortstop.

[13] Major league scouts began to take notice of deGrom when he pitched against Chris Sale of Florida Gulf Coast University.

He attempted to rehabilitate his arm for four months, but underwent Tommy John surgery to repair the UCL in October.

[17][18] He had a combined 4.51 earned run average for the season, due to a broken finger suffered during the offseason, which altered the way he threw the ball.

[8] DeGrom made his major league debut on May 15 against cross-town rival New York Yankees in Citi Field.

[23] On July 8, deGrom pitched seven scoreless innings and recorded 11 strikeouts in giving the Mets their 4,000th franchise victory.

[33] He began the 2015 season with an 8–6 win–loss record and a 2.30 earned run average through the end of June, and was named to the NL roster in the 2015 MLB All-Star Game.

He underwent season-ending surgery on his ulnar nerve in late September in order to relieve discomfort in his elbow and numbness in his fingers which had plagued him during the 2016 season.

[46] On June 18, 2017, deGrom hit his first career home run at Citi Field against Joe Ross of the Washington Nationals.

[55] During the All-Star Break, Brodie Van Wagenen, deGrom's sports agent, called for the Mets to engage in contract extension talks, or to "seriously consider trade opportunities now".

[59] On November 14, deGrom was announced as the National League Cy Young Award winner; he received all but one first place vote.

[63] DeGrom and the Mets agreed to a $17 million salary for the 2019 season, the largest annual raise ever for an arbitration-eligible player.

[64] With Van Wagenen now negotiating for the Mets rather than deGrom, the two sides agreed to a five-year, $137.5 million contract extension with an option for the 2024 season during spring training in 2019.

[75] On June 5, deGrom threw seven scoreless innings against the San Diego Padres, lowering his earned run average to 0.62, the lowest by any pitcher in history through nine starts.

On June 11, deGrom pitched six scoreless innings against the Padres, improving his earned run average to 0.56, the lowest by any pitcher through his first ten starts of the season.

Since at least 1901, no major league pitcher has had a walks plus hits to inning pitched ratio that low during 12 consecutive starts.

[77] He was named to the 2021 Major League Baseball All-Star Game, his fourth career nomination, although he announced he would not play.

[79] On July 18, deGrom began to feel tightness in his forearm during a bullpen session and was subsequently placed by the Mets onto the 10-day injured list.

[84] DeGrom made his 2022 season debut for the Mets on August 2 against the Washington Nationals, allowing one run and striking out six in five innings.

[88] At the end of the regular season, deGrom allowed at least three runs in four straight games, marking his worst stretch since 2017.

However, deGrom bounced back in Game 2 of the Wild Card Series against the San Diego Padres, as the Mets faced elimination.

Following the end of the season, deGrom opted out of his contract, joining a group of several other Mets entering free agency.

[93] On June 6, 2023, the Rangers announced that deGrom would require Tommy John surgery after suffering a torn UCL in his right elbow.

[96] DeGrom returned from Tommy John surgery and made his first major league start in 504 days on September 13, 2024, against the Mariners.

[98] He was raised by his parents, Tony, an AT&T lineman, and Tammy, a customer service representative for a credit card rewards program.

Jacob deGrom credits his father for his quiet intensity and remembers demanding sessions playing catch in their yard.