AMPA receptors (AMPARs) are the main drivers of excitatory glutamatergic transmission in the brain, central to synaptic plasticity, and are key drug targets. However, AMPARs are expressed in virtually every neuron in the central nervous system and are activated with complex temporal dynamics, making it difficult to determine their functional roles with sufficient precision. Here we describe a cell specific, light-controllable competitive antagonist for the AMPA receptor called MP-GluAblock that combines the temporal precision of a photo-switchable ligand with the spatial and cellular specificity of a genetically-encoded membrane-anchor protein. This tool could pave the way for controlling endogenous AMPARs in neural circuits with cellular, spatial, and temporal specificity.