A highly sensitive electrochemiluminescence (ECL) sensor for 3-monochloropropane-1,2-diol (3-MCPD) was successfully developed using a [Ru(bpy)₃]2+/triethylamine system integrated with the molecularly imprinted polymer (MIP) technique. Polyaniline (PANI) was selected to modify the screen-printed carbon electrode (SPCE) to provide an active site that facilitates ion mobility and charge transfer in the biocompatibility interactions. The molecular interaction between PANI and 3-MCPD was evaluated using density functional theory (DFT), which revealed a favourable interaction energy, confirming the strong affinity and high selectivity of the proposed sensor toward 3-MCPD. In the ECL system, 3-MCPD efficiently quenched the luminescence of [Ru(bpy)₃]2+, indicating its strong interaction within the sensing mechanism. The sensor achieved a detection limit of 21.68 nM with a sensitivity of 0.22 a.u. nM−1 mm−2, confirming its high analytical performance for 3-MCPD detection. High ECL selectivity was achieved through integration with the MIP approach, enhancing target molecular recognition and offering a new pathway for designing robust sensors for food contaminant monitoring. Moreover, the integration of computational prediction with experimental validation provides a robust strategy for designing selective and sensitive detection platforms. The proposed sensor was successfully applied for 3-MCPD detection in a cooking oil matrix, demonstrating its applicability in spiked oil matrices under controlled laboratory conditions. © 2026 Elsevier B.V.