Arozarena signed with St. Louis Cardinals as an international free agent in July 2016 for $1. 25 million. He made his minor league debut in 2017 and spent his first full professional season with both the Palm Beach Cardinals, with whom he was named a Florida State League All-Star, and the Springfield Cardinals, posting a combined . 266 batting average with 11 home runs, 49 RBIs and 18 stolen bases over 121 games between both clubs. Following the season, he returned to the Mexican Pacific League to play for the Mayos de Navojoa for the 2017–2018 season, where he slashed . 292/. 366/. 558 with 14 home runs and 37 RBIs in 64 games. That season the Mayos made it to the championship series, though the team did not win the series, Arozarena had a game winning hit in the bottom of the ninth inning in game 6. Arozarena was a non-roster invitee to 2018 spring training. He began the season with the Memphis Redbirds. In July 2018, he was selected to represent the Cardinals in the 2018 All-Star Futures Game. Arozarena also spent time during the season with Springfield. With Memphis, he helped them win the Pacific Coast League title, and was named a co-MVP of the PCL playoffs alongside teammate Tommy Edman. Over 113 games between Memphis and Springfield, he batted . 274/. 359/. 433 with 12 home runs, 49 RBIs, and 26 stolen bases. Arozarena returned to play for Mayos de Navojoa in 2018 for the third time, but appeared in only 15 games.