Houston designated Pearson for assignment on Sunday, Matt Kawahara of the Houston Chronicle reports.
The 29-year-old will lose his spot on the 40-man roster after he turned in a 3.60 ERA, 1.40 WHIP and 16:12 K:BB in 20 innings while serving as a middle-relief option for Houston. The Astros called up infielder Raynel Delgado from Triple-A Sugar Land to take Pearson's spot on the 26-man active roster.