Surface structures and surface interactions are key factors that influence the reactivity and stability of nanomaterials. Combining experimental and theoretical investigations, we illustrate the roles of surface interactions in the formation and phase stability of an unusual TiO2(B) polymorph that preferentially exposes the plane of the highest surface energy. We find that the favorable bidentate adsorption of ethylene glycol on the TiO2(B)(010) plane enables the formation and confines the phase stability of TiO2(B) ultrathin nanosheets. The essence of such selective generation of the unusual nanostructure with ultrahigh purity both in phase and morphology lies in the specific adsorption driven by the matched interface structures. The general roles of structural match for the activity and stability in physical interactions are elucidated.