Excitonic insulators host the condensates of bound electron–hole pairs, offering a platform for studying correlated bosonic quantum states and for next-generation device applications. However, how macroscopic coherence emerges from locally collapsed pairing remains elusive. Here, using scanning tunnelling spectroscopy, we report the impurity-induced pair breaking in the excitonic insulator Ta2Pd3Te5. Individual Te vacancies generate a pair of spectral peaks within the excitonic gap. Their energies depend sensitively on the defect configurations and are continuously tunable using tip electric field, indicating controllable impurity scatterings. Spectral mapping shows spatially anisotropic and electronically coupled electron–hole components of the subgap states. These observations, together with mean-field modelling, suggest an excitonic pair-breaking origin. In the strongly electron–hole-imbalanced region, a secondary pair-breaking effect, manifesting an additional pair of subgap states with distinctly lower energies, emerges and displays the interplay of pairing breakings with different excitonic order parameters. Our findings demonstrate the spectroscopic fingerprint of local excitonic depairing at the atomic level, offering a crucial clue to the critical behaviour across excitonic condensation.