Mosquito-borne diseases continue to represent a major global health burden, particularly in tropical and subtropical regions where environmental conditions favor mosquito breeding and survival. Vector species such as Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus are responsible for the transmission of dengue, malaria, chikungunya, Zika virus infection, Japanese encephalitis, and lymphatic filariasis. Chemical insecticides remain the most widely used tools for vector control through indoor residual spraying, insecticide-treated bed nets, larviciding, and space spraying. However, the continuous and often indiscriminate use of insecticides has resulted in the rapid development of resistance in mosquito populations across the world. This research project investigates the occurrence and intensity of insecticide resistance in selected mosquito populations and examines the biochemical and molecular mechanismsunderlyingresistancedevelopment. Standard WHO susceptibility bioassays, enzyme activity assays, and molecular diagnostic techniques were employed to determine resistance status and identify genetic mutations associated with reduced insecticide sensitivity. The results revealed high levels of resistance to pyrethroids and organochlorines, moderate resistance to organophosphates, and comparatively lower resistance to carbamates. Elevated detoxification enzyme activity and the presence of knockdown resistance (kdr) mutations were identified as major mechanisms contributing to resistance. The findings emphasize the urgent need for continuous resistance monitoring and integrated vector management strategies to ensure sustainable mosquito control and disease prevention.