Abstract Synthetic insecticides may pose significant environmental and health risks, thereby driving the demand for effective, biodegradable alternatives. This study reports the development and validation of a multifunctional biopesticide with a potentially reduced environmental footprint, based on an oil-in-water emulsion of essential oils encapsulated within a carboxymethylcellulose biopolymer matrix. The formulation was comprehensively evaluated for its bioactivity against the green peach aphid (Myzus persicae) and the meadow tick (Dermacentor reticulatus), its phytotoxicity on non-target model plants (Nicotiana tabacum and Brassica napus), and its mechanism of action via in silico molecular docking and molecular dynamics simulations. The emulsion demonstrated dual-action efficacy, achieving 100% mortality against aphids within 24 h. Furthermore, it exhibited potent and long-lasting repellency against ticks, with statistical modeling confirming that its high efficacy was sustained throughout the 240-minute test period. Phytotoxicity assessments revealed no phytotoxic effects on mature leaves of Nicotiana tabacum and Brassica napus, while germination and seedling growth tests indicated moderate, concentration-dependent inhibitory effects. Molecular docking studies suggested plausible binding interactions of key terpenoids (linalool, α-pinene) with neurological targets in both pests, including acetylcholinesterase and the octopamine receptor, as hypothetical mechanistic bases for the observed bioactivity. Molecular dynamics simulations confirmed the stability of the linalool–OBP3, linalool–AChE2, and α-pinene–octopamine receptor complexes, while the α-pinene–histamine-binding protein complex showed progressive ligand displacement, indicating a less stable interaction. This work presents a successful strategy for creating an effective dual-action biopesticide with a favorable predicted safety profile, and highlights the carboxymethylcellulose matrix as a critical technological component that mitigates the inherent phytotoxicity of essential oils while preserving their pest-control activity. These findings represent a contribution to the development of sustainable integrated pest management tools. Keywords: Biopesticide; Essential oils; Integrated pest management; Sustainable agriculture