Rumex hastatus is known for its nutritional and pharmacological properties. The present research explored ultrasound‐assisted extraction (UAE) for antioxidants from it. Response surface methodology (RSM) was used with the Box–Behnken design. Hydro‐ethanolic solvent ratio, amplitude, and temperature were the independent factors while % extraction yield, total phenolic content (TPC), total flavonoid content (TFC), antioxidant potential, and metal chelating activity (MCA) were the responses. The highest extraction yield was 11.58% that was obtained at 20% hydro‐EtOH, 50℃ temperature, and 50 m amplitude. The optimum conditions for the highest TPC were 80% hydro‐EtOH, 60℃ temperature, and 75 m amplitude, for the highest TFC were 80% hydro‐EtOH, 50℃ temperature, and 50 m amplitude. For MCA, the optimum conditions were 20% hydro‐EtOH solvent, 50℃ temperature, and 100 m amplitude, respectively. UAE proved to be an efficient green technique for the extraction of bioactive and antioxidant substances from R. hastatus. Practical applications The findings of this study are important for experts and industries related to vegetables and their antioxidant substances. The optimization work will be useful for the development of an efficient method for extraction of bioactive natural products from this plant for large‐scale production.