The emissive properties of two Ru(II) complexes, [Ru(dmbipy)2L1][PF6]2 (1) and [Ru2(dmbipy)4L2][PF6]4 (2), (where L1 and L2 are π-extended phenanthroline-based ligands and dmbipy = 4,4'-dimethyl-2,2'-bipyridine) have been explored for dual applications, namely, deep-red light-emitting electrochemical cells (LECs) and electrochemiluminescence (ECL) sensors for the detection of organophosphorus pesticides (OPs) that include chlorpyrifos (CPS). A simple single-layer deep-red LEC device comprising 2 is reported that outperforms both its mononuclear derivative 1 and all previously reported dinuclear LECs, with a maximum brightness of 524 cd/m2, an external quantum efficiency of 0.62%, and a turn-on voltage of 3.2 V. Optoelectronic studies reveal that the ECL response of 2 is improved when compared to its mononuclear counterpart 1 and benchmark [Ru(bipy)3]2+ (3). Modified glassy carbon electrodes coated with 2 are highly sensitive deep-red ECL sensors that facilitate the detection of CPS directly from river water and fruit samples without any complex pretreatment steps, operating over a broad logarithmic concentration range, with a low detection limit.