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Fluorescent probes based on molecular rotor are expected to be a powerful tool to uncover the relationship between intracellular viscosity and organelle functions as well as related diseases. Herein, a fluorophore MV-indol containing multiple rotors was constructed by linking triphenylamine group and benzindole unit. It was found that MV-indol can quantitatively detect viscosity with a high selectivity and a 75-fold enhancement in quantum yield (QY). Moreover, the viscosity-sensitive property could be ascribed to the inhibition of molecular rotation and restriction of twisted intramolecular charge transfer (TICT) in a high-viscous environment, which was confirmed by time-dependent density functional theory (TD-DFT). Importantly, we also demonstrated that MV-indol can precisely localize in mitochondria and monitor the change of mitochondrial viscosity at the cellular level.