A novel one‐pot diastereoselective synthesis of trans‐6‐aryl‐5‐hydroxy‐2,3‐dihydro[2,3‐c]pyrazol‐4(1H)‐ones 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h is described via the Darzens condensation reaction of 2‐chloro‐1‐(5‐hydroxy‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐4‐yl)ethanone (2) with different aromatic aldehydes in aqueous basic medium. The structures of the compounds prepared were determined by analytical and spectral analyses.