Natural selection over billions of years has developed highly effective in vivo signal transduction that is often governed by a series of competitive multiple mechanisms. Several artificial signal transduction pathways have inspired numerous biosensing systems, but most of these are driven by a single mechanism. Herein we describe a multiple-mechanism-driven electrochemiluminescent (ECL) biosensor that utilizes competitive catalytic and steric hindrance effects by assembling hemin/G-quadruplex on carbon nitride nanosheets. Taking the detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) as example, the dynamic ranges of the detectable concentrations from the different mechanisms were integrated into a single sensor interface. Moreover, the detection sensitivity was more precisely controlled by the competition between the two mechanisms and inherently boosted compared with that of single-mechanism-driven detection. Going beyond the conventional single-mechanism-driven biosensing, the elaborate biomimetic coupling of multiple mechanisms in a single interface may open a new approach for future multiplexed biosensing.