Aqueous anion recognition using artificial receptors is of great interest but full of challenges. Typically, anion-selective receptors are designed by selecting scaffolds that have either hydrogen bonding sites or positively charged moieties. Herein, we constructed an acetate-responsive chromogenic molecular switch with a phenolphthalein backbone and achieved the visual recognition of acetate in pure water. UV–Vis and 1H NMR titration data reveal that the molecular switch receptor has good selectivity and binding towards acetate. Mechanistic studies have shown that this molecular switch-type anion receptor recognizes acetate through hydrogen bonding to facilitate proton transfer. Our findings are expected to pave the way for a new class of aqueous anion receptors and the development of new molecular recognition mechanisms. A novel phenolphthalein-based molecular switchable anion receptor is capable of highly selective recognition of acetate in water via hydrogen bonding-induced proton transfer mechanisms. Display omitted •New phenolphthalein-based molecular switched receptors for acetate were designed.•Solvent polarity governs the ratio of colored ring-opening to colorless ring-closed in molecular switch.•Acetate in pure water can be easily recognized with this receptor through the naked eye.•Acetate recognition mechanism involves hydrogen bonding-induced proton transfer.