In 2018, he spent the majority of the year back in the Arizona League in which he went 2–2 with a 2.18 ERA over 11 games (nine starts), striking out 58 over 45+1⁄3 innings.

[14][15][16][17][18] After pitching to a 9–3 record and a 1.98 ERA while striking out 128 batters over 98 innings (19 starts) with Fort Wayne, he was promoted to the Lake Elsinore Storm of the High–A California League in August.

[19][20] With Lake Elsinore, Cantillo made three starts in which he compiled a 4.61 ERA before being shut down for the season due to reaching his innings limit.

[21] On July 31, 2020, the Padres traded Cantillo, Austin Hedges, Cal Quantrill, Josh Naylor, Gabriel Arias, and Owen Miller to the Cleveland Indians in exchange for Mike Clevinger, Greg Allen, and Matt Waldron.

[29] On November 15, 2022, the Guardians selected Cantillo's contract and added him to the 40-man roster, protecting him from the Rule 5 draft.

[32] In 26 games (24 starts) between Akron and Columbus, he posted a combined 7–4 record and 4.07 ERA with 146 strikeouts across 119+1⁄3 innings of work.