The arsenomolybdates [H2As2Mo6O26(H2O)]·(H2biyb)2·2H2O (1) and [H3As2Mo6O26]·(H3pt)2 (2) [biyb = 1,4‐bis(imidazol‐1‐ylmethyl)benzene, pt = 4′‐(3′′‐pyridyl)‐2,3′:6′3′′‐terpyridine] were synthesized via hydrothermal method. The structures of the compounds were characterized by single‐crystal X‐ray diffraction analyses, elemental analyses, IR spectroscopy, and TG analysis. Compounds 1 and 2 exhibit two isomeric forms of [HxAs2Mo6O26](6–x)–. The structure of 1 is constructed from the B‐type [H2As2Mo6O26(H2O)]4– polyanions and free biyb ligands via weak interactions to form 3D supramolecular framework with a {3·4·53·6}{3·43·52}{3·5·6}2{3·52}2 topology structure. In compound 2, the A‐type [H3As2Mo6O26]3– clusters are surrounded by pt ligands through hydrogen bond interactions forming 3D supramolecular framework with a {43·63}2{46·66·83} topology structure. The electrochemical behaviors, electrocatalytic and photocatalytic activities of 1 and 2 are detected.