In the present study, mosquito larvicidal and repellent activity and phytochemical screening of the horse chestnut, Aesculus hippocastanum seeds extract have been evaluated against Culex pipiens mosquito. The obtained results indicated that there was a positive correlation between the concentration of Aesculus hippocastanum seeds extract and the total larval and pupal mortality percent, the recorded LC₅₀ was 122 and 76 ppm for larvae and pupae, respectively. In addition, a remarkable reduction in both the pupation and adult emergence percent were obtained. Also, the extract showed prolonged activity on both larval and pupal duration. Moreover, various degrees of morphogenic abnormalities were observed in the immature and adult stages. The antifeedant and repellent activity of the present plant extract was investigated, it exhibits the highest protection (100%) from the bites of starved females at the dose of 3mg/cm². the major bioactive chemical constituents in Aesculus hippocastanum seeds extract were identified using HPLC and FT-IR analysis.These results suggested the Aesculus hippocastanum seeds extract as a promising adult emergence inhibitor and repellent agent against the vector mosquitoes and might be used in small volume aquatic habitats or other breeding sites of mosquitoes.