The Astros selected Hernandez's contract from Triple-A Sugar Land on Wednesday, Matt Kawahara of the Houston Chronicle reports.
Hernandez was acquired via trade from the Padres on Tuesday and has now been added to the 40-man roster and 26-man active roster. The 29-year-old boasts a 1.90 ERA and 34:9 K:BB over 23.2 innings at the Triple-A level in 2024. He made two relief appearances with San Diego in 2023, allowing four frames in three frames.