He has previously played in Major League Baseball (MLB) for the Houston Astros and Arizona Diamondbacks.

In 2019, he split the season between Quad Cities, High-A Fayetteville Woodpeckers, and Triple-A Round Rock Express.

[2] On August 4, he made his MLB debut against the Arizona Diamondbacks and pitched a scoreless ninth inning.

[3] He made 8 appearances for Houston in his rookie campaign, posting a 6.75 ERA with 12 strikeouts in 10+2⁄3 innings of work.

[7] After missing all of 2023 in rehabilitation, Castellanos began the 2024 campaign with Triple–A Reno, recording a 4.57 ERA across 10 games (9 starts).

[11] On February 6, 2025, Castellanos signed with the CTBC Brothers of the Chinese Professional Baseball League.