A viologen derivative carrying a benzimidazole group (V‐P‐I 2+; viologen–phenylene–imidazole V‐P‐I) can be dimerized in water using cucurbit[8]uril (CB[8]) in the form of a 2:2 complex resulting in a negative shift of the guest pKa, by more than 1 pH unit, contrasting with the positive pKa shift usually observed for CB‐based complexes. Whereas 2:2 complex protonation is unclear by NMR, silver cations have been used for probing the accessibility of the imidazole groups of the 2:2 complexes. The protonation capacity of the buried imidazole groups is reduced, suggesting that CB[8] could trigger proton release upon 2:2 complex formation. The addition of CB[8] to a solution containing V‐P‐ I3+ indeed released protons as monitored by pH‐metry and visualized by a coloured indicator. This property was used to induce a host/guest swapping, accompanied by a proton transfer, between V‐P‐I 3+⋅CB[7] and a CB[8] complex of 1‐methyl‐4‐(4‐pyridyl)pyridinium. The origin of this negative pKa shift is proposed to stand in an ideal charge state, and in the position of the two pH‐responsive fragments inside the two CB[8] which, alike residues engulfed in proteins, favour the deprotonated form of the guest molecules. Such proton release triggered by a recognition event is reminiscent of several biological processes and may open new avenues toward bioinspired enzyme mimics catalyzing proton transfer or chemical reactions.