This study investigated the repellent and insecticidal effectiveness of catnip (Nepeta cataria L.) leaf extract against mosquitoes with a view to formulating an effective repellent and an alternative to the gold-standard synthetic DEET (N, N-diethyl-3-methylbenzamide) repellent. The leaves were extracted using ethyl acetate, and the extract was prepared at five different (5, 10, 20, 50, and 100 %) concentrations. Mosquito repellency tests were conducted using arm-in-cage trials, in which a control arm and an arm treated with the extract were placed in a cage containing a predetermined number of unfed mosquitoes. A similar setup was used, but with a synthetic DEET-based product (Odomos) acting as a positive control. The result of the repellency study showed that at concentrations of ≥10%, the extract effectively repels mosquitos, according to efficacy studies. There was no substantial difference in the extract’s repellent properties vs Odomos. Mortality test results show that the extract lacks acute toxicity at low dosages (5%), with mortality rates increasing significantly as concentrations scaled. Lethality rose from 8.67% at a 10% concentration to 27.78% at 20%, eventually peaking at 39.62% at the 100% dosage. A critical efficacy threshold was identified between the 10% and 20% concentrations, suggesting that bioactive compounds—potentially nepetalactones—reach levels sufficient to disrupt insect physiological activity within this range. While the extract’s performance remained lower than the positive control (which peaked at 49.22%), the narrow margin at high dosages underscores its potency. These findings support the potential of ethyl acetate extract of N. cataria as a viable, eco-friendly alternative to conventional synthetic insecticides. It also indicated that the plant extract could be utilized in mosquito control management in two ways: it could be utilized at low concentrations to formulate mosquito repellents and at high concentrations to produce insecticides.