Pericytes line the microvasculature throughout the body and play a key role in regulating blood flow by constricting and dilating vessels. However, the biophysical mechanisms through which pericytes transduce microenvironmental chemical and mechanical cues to mediate vessel diameter, thereby impacting oxygen and nutrient delivery, remain largely unknown. This knowledge gap is clinically relevant as numerous diseases are associated with the aberrant contraction of pericytes, which are unusually susceptible to injury. Here, we report the development of a high-throughput hydrogel-based pericyte contraction cytometer that quantifies single-cell contraction forces from murine and human pericytes in different microvascular microenvironments and in the presence of competing vasoconstricting and vasodilating stimuli. We further show that murine pericyte survival in hypoxia is mediated by the mechanical microenvironment and that, paradoxically, pre-treating pericytes to reduce contraction increases hypoxic cell death. Moreover, using the contraction cytometer as a drug-screening tool, we found that cofilin-1 could be applied extracellularly to release murine pericytes from hypoxia-induced contractile and, therefore, may represent a novel approach for mitigating the long-lasting decrease in blood flow that occurs after hypoxic injury.