In this study, a novel and innovative enzyme-free electrochemiluminescence (ECL) pesticide probe based on a ternary nanocomposite, CuS/CQDs/g-C3N4NS, was demonstrated for the accurate monitoring of chlorpyrifos. Boron nitride quantum dots were introduced as a new and effective coreactant in comparison with other coreactants, such as hydrogen peroxide, peroxydisulfate, and tripropylamine, in the negative potential range for the first time. The nanocomposite as a promoted luminophore was synthesized by a one-pot microwave route. Carbon quantum dots and copper sulfide nanostructures were truly incorporated on the porous graphitized carbon nitride, which displayed a good cooperative effect on the signal improvement. CuS as a co-reaction accelerator and CQDs with a superior luminescence effect produced more radical species, and thus, the ECL signal was amplified. Upon increasing the appropriate concentration of this coreactant in electrolyte media, the signal intensity of the nanocomposite increases. A low detection limit of 3.0 × 10-16 M and a wide range from 2.0 × 10-15 to 7.0 × 10-9 M were gained. Also, the fabricated pesticide sensor presented excellent repeatability for 20 consecutive optical signals, with a RSD of about 1.4%. Owing to its high proficiency, the developed sensor was applied as a new probe for chlorpyrifos analysis in water and fruit samples.