We applied high‐speed photoacoustic microscopy (PAM) for both cortical microenvironment studies and dynamic brain studies, with micrometer‐level optical resolution and a millisecond‐level cross‐sectional imaging speed over a millimeter‐level field of view. We monitored blood flow redistribution in mini‐stroke mouse models and cerebral autoregulation induced by a vasoactive agent. Our results collectively suggest that high‐speed PAM is a promising tool for understanding dynamic neurophysiological phenomena, complementing conventional imaging modalities. magnified image