Photoinduced Rydberg ionization (PIRI) spectroscopy has been applied to the problem of recording vibrationally resolved spectra of the dipole-forbidden B̃ 2E2g←X̃ 2E1g transition of C6H6+ and C6D6+. PIRI spectra of the B̃ state have been recorded via a number of vibrational states of the ionic ground state. A combination of Herzberg–Teller and pseudo-Jahn–Teller vibronic coupling between the B̃ state and a close lying C̃ state were used to explain the complex B̃ state vibrational structure. The two pseudo-Jahn–Teller vibrational modes, ν16 and ν17, were both found to be active in the PIRI spectra. In addition, evidence for a strong pseudo-Jahn–Teller interaction within each of these modes was found. The perturbed vibronic bands resulting from this pseudo-Jahn–Teller activity were successfully modeled using a two-mode pseudo-Jahn–Teller vibronic coupling model. Using a combination of the spectral results and the pseudo-Jahn–Teller calculations, we were able to generate absolute vibronic symmetry assignments for many of the lower B̃ state vibrational levels, from which vibrational assignments were made. The calculations also produced unperturbed vibrational frequencies for both pseudo-Jahn–Teller active modes along with values for their respective linear coupling constants.