Herein, a label‐free and immobilization‐free electrochemiluminescence resonance energy transfer (ECL‐RET) system based on graphitic carbon nitride nanosheets (GCNNs)/Ru(phen)32+ donor/acceptor pair is developed, in which the ECL‐RET is regulated by regulating the diffusivity of Ru(phen)32+ molecules toward the negatively charged GCNNs through logically programmed DNA hybridization reactions. The two optical signals of GCNNs (445 nm) and Ru(phen)32+ (593 nm) show completely opposite changes through the same one‐time DNA hybridization reaction. Based on this ECL‐RET system, a contrary logic pair (CLP) library, a parity generator/checker system for differentiating the erroneous bits during data transmission, the parity checker to identify the even/odd natural numbers from 0 to 9, and a series of concatenated logic circuits including a six‐input logic gate capable of implementing of 64 input combinations for meeting the needs of computational complexity are developed. The ECL‐RET‐based molecular logic system avoids the time‐consuming, costly and inefficient labeling procedures and the laborious processes of immobilization, presenting great potential for building more complicated and advanced logic gates, and providing a refreshing inspiration for the construction of combinatorial logic circuits based on ECL method. An electrochemiluminescence resonance energy transfer (ECL‐RET) system is proposed for constructing contrary logic pair (CLP) library, even^odd parity generator/checker (Pg/Pc) system and various concatenated logic circuits based on the intercalation of Ru(phen)32+ into double‐stranded DNA and its diffusion toward the negatively charged graphitic carbon nitride nanosheets (GCNNs).