Chemical weed control method caused environmental hazards and residual effects in crops and soil. Alternate approach to control weeds is getting attentions in sustainable production system. Use of aqueous extracts of weed is getting scientific attention as eco-friendly alternative to chemical herbicides especially under scenario of fast increasing herbicide resistance in weeds. To investigate the herbicidal potential of aqueous extract of winter weed of Sonchus oleraceus L. (sow thistle) on summer weed Oryza punctata L. (red rice) seed emergence and initial seedling growth, the present study was planned. In this study, seeds of O. punctata were incubated in seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different parts i.e. leaf, stem and flower of S. oleraceus. All the tested concentrations of various plant parts significantly inhibited the mean emergence time, emergence index, emergence percentage (%), time taken to 50% emergence as well as growth of O. punctata. However, maximum mean emergence time (5.26 days), minimum germination index (1.69), germination percentage (40%), root length (2.04 cm), shoot length (5.71 cm), fresh weight (59 g), dry weight (4.06 g) was noted at 8% concentration with fruit aqueous extract. Seeds of O. punctata took maximum time to complete 50% emergence (3.33 days) under control where we applied distilled water. Results suggested that the fruit extract of S. oleraceus at 8% concentration can be used potential bio-herbicide for the control of O. punctata.