The present study investigated the phytochemical composition, larvicidal efficacy, and biochemical effects of the hydro-ethanolic extract of Retama sphaerocarpa aerial parts against Culiseta longiareolata larvae. Retama sphaerocarpa hydro-ethanolic extract was tested at different concentrations ranging between 100 and 1600 ppm; 200 and 2000 ppm on newly molted third and fourth-instar larvae, respectively. Under standard laboratory conditions in conformity with World Health Organization (WHO) recommendations. The effects were assessed in terms of mortality, the activities of glutathione S-transferase and catalase, body development, and the biochemical composition of larval stages. The LC/MS profile revealed a predominance of phenolic compounds, particularly ferulic acid and flavonoids, together with detectable levels of alkaloids. The quantitative evaluation indicated that the aerial parts of R. sphaerocarpa hydro-ethanolic extract afforded 25.65 ± 3.49%. Its phenolic compounds have been investigated by HPLC. Seven compounds have been detected. The major compounds were: rutin (22.98%) and catechin (19.64%). The hydro-ethanolic extract exhibited pronounced larvicidal activity in a dose- and time-dependent manner. It induces 100% mortality at the concentrations of 1600 and 2000 ppm for third and fourth-instar larvae of Cs longiareolata, respectively. Enzymatic assays conducted on LC25 and LC50 treated larvae indicated neurotoxic activity and stimulation of the detoxification system, as supported by an increase in GST and catalase activities. Also, the development study indicated a significant reduction in the weight and volume of body under the effect of the treatment by R. sphaerocarpa hydro-ethanolic extract for the larval stages. Moreover, biochemical analyses of larvae exposed to LC25 and LC50 concentrations demonstrated significant reductions in total proteins, carbohydrates, and lipids after 24-72 h of exposure. Overall, these findings highlight R. sphaerocarpa as a promising botanical source for the development of safe, effective, and eco-friendly mosquito control agents.