We designed and synthesized a new and novel octahedral hexamolybdenum(II) cluster bearing terminal pyridine‐3‐carboxylate (3L) or pyridine‐4‐carboxylate ligands (4L), [{Mo6Br8}(3L)6]2– (3) or [{Mo6Br8}(4L)6]2– (4), to demonstrate proton‐switched emission behaviour of the cluster. X‐ray crystal analysis of 4 demonstrated that the O‐atom in the carboxylate group of 4L coordinates to each Mo atom in the {Mo6Br8}4+‐core, indicating that the N‐atom of 4L in 4 is open for protonation. Reflecting such structural characteristics of the cluster, both 3 and 4 showed proton‐switched emission behaviour owing to the changes in the electron‐donating abilities of the relevant terminal ligands upon protonation to the pyridine N atoms: blue shifts of the emission spectra and increases in the emission lifetimes of the clusters.