Robertson started 30 games at second base as a freshman, but batted .200 with one home run and 20 RBIs. He batted .232 as a sophomore.[2] In 2014 and 2015, he played collegiate summer baseball with the Wareham Gatemen of the Cape Cod Baseball League, where he was named a league all-star in 2014.[4][5][6] During his junior year, he moved to shortstop. He batted .324 with two home runs, 39 RBIs, 20 doubles, and 14 stolen bases as a junior in 2016, and was named to the All-Southeastern Conference team and Collegiate Baseball'sAll-American team.[1][7] The Cleveland Indians selected Robertson in the 32nd round of the 2016 MLB draft, but he did not sign, turning down a $250,000 signing bonus so that he could return to LSU for his senior year.[8][9] As a senior, he batted .307 with eight home runs, 43 RBIs, 18 doubles, and 85 runs scored.
The St. Louis Cardinals selected Robertson in the fourth round of the 2017 MLB draft.[10] He signed with the Cardinals,[11] and made his professional debut for the Peoria Chiefs.[12] He spent the whole season with Peoria, batting .270 with three home runs, 13 RBIs, and ten stolen bases in 54 games.[13] Robertson spent 2018 with the Palm Beach Cardinals where he compiled a .252 batting average with two home runs, 37 RBIs, and 15 stolen bases in 121 games.
Robertson began the 2019 season with the Springfield Cardinals,[14] and also spent time with the Memphis Redbirds. Over 123 games between the two clubs, he slashed .231/.360/.365 with 11 home runs, 51 RBI, and 14 stolen bases.[15] He was selected to play in the Arizona Fall League for the Glendale Desert Dogs following the season.[16] Robertson did not play in a minor league game in 2020 due to the cancellation of the season as a result of the COVID-19 pandemic.[17] Robertson played for Memphis in 2021[18] and began the season with Memphis in 2022.[19]
On May 10, 2022, the Cardinals promoted Robertson to the major leagues.[20] He made his MLB debut that night as a pinch runner.[21] In his second and final game in the majors that year he hit an RBI groundout. He was designated for assignment on June 3, following the promotion of Zack Thompson.[22]
The New York Mets claimed Robertson off of waivers from the Braves on June 27, 2022.[24] Robertson was designated for assignment by the Mets on August 3.
Robertson spent the 2023 season with Triple–A Memphis, playing in 121 games and hitting .205/.356/.262 with 3 home runs, 37 RBI, and 23 stolen bases. On October 13, 2023, Robertson was released by the Cardinals organization.[27]
Robertson’s mother is Kim Mulkey, current head coach of the LSU women’s basketball team. He has an older sister, Makenzie, who played college basketball at Baylor.[2][10]