De Jong was drafted by the Toronto Blue Jays out of Woodrow Wilson High School in Long Beach, California in the 2nd round of the 2012 Major League Baseball Draft. After signing for a bonus of $620,300, De Jong was assigned to the Gulf Coast League Blue Jays and made 6 relief appearances for the team, posting a 1–0 record with a 1.50 earned run average and 15 strikeouts over 12 innings, with only 1 walk. He was promoted to the Bluefield Blue Jays prior to the start of the 2013 season, and made 13 appearances for the team, 10 of which were starts. In 2013, De Jong posted a 2–3 record with an ERA of 3.05 and 66 strikeouts over 56 innings pitched. In 2014, he was promoted to the Class-A Lansing Lugnuts. De Jong made 23 appearances for Lansing in 2014, 21 of which were starts, and compiled a record of 1–6 with a 4.82 ERA and 73 strikeouts in 97 innings pitched. De Jong started the 2015 season in Lansing, making 14 starts and posting a 7–4 record, 3.13 ERA, and 77 strikeouts in 86 innings.
DeJong was traded to the Los Angeles Dodgers on July 2, 2015 for cash. In 11 appearances for the Rancho Cucamonga Quakes he was 4–3 with a 4.86 ERA. He struck out six in six innings for the Quakes in the opening game of the California League championship series. The Dodgers invited him to major league spring training in 2016. To start the 2016 season, he was promoted to the Double-A Tulsa Drillers of the Texas League, where he was selected to the mid-season all-star team. In Tulsa, he developed a cut fastball under the tutelage of pitching coatch Bill Simas. After the season, he was named to the post-season all-star team and honored as the Texas League Pitcher of the Year. In 25 starts for the Drillers he was 14–5 with a 2.86 ERA, earning him a late season promotion to the Triple-A Oklahoma City Dodgers, where he allowed one run in 5 innings in his one start. The Dodgers added him to their 40-man roster after the season.
On July 30, 2018, De Jong was traded to the Minnesota Twins along with infielder for Ryan Costello for pitcher Zach Duke. He was called up in September of that year. On January 30, 2019, De Jong was designated for assignment after the signing of Martin Perez was made official. He was outrighted on February 6. DeJong had his contract selected on April 6, 2019. After a game against the Mets where he gave up 4 earned runs, 1 home run, and 3 walks in 1 inning pitched, he was sent back down to Triple-A Rochester. DeJong was outrighted off the roster on April 26, 2019.
Sugar Land Skeeters
On July 22, 2019, De Jong signed with the Sugar Land Skeeters of the Atlantic League of Professional Baseball. He became a free agent following the season. On April 1, 2020, De Jong re-signed with the Skeeters for the 2020 season.
Personal life
He is the cousin of former Blue Jays pitcher Jordan De Jong.
