A one‐step synthesis procedure for starch‐based acrylate superabsorbent polymers was proposed. The reaction conditions that may affect the water absorption capacity were discussed. A transparent gel‐like polymer containing urea (USAP) was successfully obtained by dissolving starch in a NaOH solution without further gelatinizing processing and using AA directly without prior neutralization. Urea was used as the nitrogen source and pore‐forming agent to improve the performance of the USAP. The optimum reaction conditions of the swelling ratio were also studied. A corn starch USAP was synthesized under the optimum conditions, and the water absorbency was 2704 ± 22, 561 ± 39, 100 ± 5, and 96 ± 4 g/g, respectively, in distilled water, running water, physiological saline, and artificial urine. Five kinds of starch‐based USAPs were also successfully prepared under the same conditions with excellent water absorption capacities, revealing that the one‐step method was a more convenient method for a potential industrial application pathway. The polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The results indicated that the PAA chains were successfully grafted onto the St backbone. However, the St molecular structure was not completely destroyed during the graft polymerization. The thermal analysis and nitrogen content results proved that urea was also involved in the graft copolymerization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45175.