The 3,4‐ethylenedioxy thiophene (EDOT)‐based conjugated microporous polymers (CMPs) were readily constructed via facile one‐step direct arylation polymerication of CH from simple EDOT as a linker and commercially available aryl bromides of different geometries as the knots, without preactivation of CH bonds of aromatic building blocks using organometallic reagents. In contrast to conventional coupling reactions, this synthesis strategy not only has atomic efficiency but also can use simple thiophene derivatives as building blocks for synthesizing thiophene‐based CMPs of different structures, which avoids the synthesis of complex thiophene derivatives and are important for applications, for example, fluorescent sensors. The resulting EDOT‐based CMPs were used to fluorescent sensing to 2,4‐dinitrophenol (DNP), I2, and p‐nitrophenol (p‐NP), with high optimal Stern‐Volmer quenching constants.