Conjugated microporous polymers (CMPs) represent a rapidly advancing group of metal-free organic photocatalysts, offering a sustainable route for hydrogen (H₂) generation through photocatalytic water splitting. Their intrinsic permanent porosity, combined with extended π-conjugation and large surface areas, enables superior light harvesting, efficient exciton dissociation, and accelerated molecular diffusion—key attributes for effective photocatalytic systems. In this study, two newly developed CMPs—Py–Thio–Tri CMP and Py–Thio–PyD CMP—were synthesized and subjected to rigorous physicochemical characterization to investigate their photocatalytic performance. Nitrogen adsorption–desorption measurements were employed to determine their porosity. The chemical structures and functional group integrity were validated via Fourier-transform infrared (FT-IR) spectroscopy. Photocatalytic evaluations demonstrate that Py–Thio–Tri CMP exhibits markedly superior hydrogen evolution activity compared to Py–Thio–PyD CMP. Specifically, Py–Thio–Tri CMP achieves an initial hydrogen generation rate (HGR) of 1100 μmol h⁻¹ g⁻¹ within the first hour of irradiation, substantially surpassing the 182 μmol h⁻¹ g⁻¹ recorded for Py–Thio–PyD CMP under similar circumstances. Upon incorporation of 3 wt % cobalt (Co) as a cocatalyst, the HGRs further increased to 1242 and 249 μmol h⁻¹ g⁻¹ for Py–Thio–Tri CMP and Py–Thio–PyD CMP, respectively. Additionally, transient photocurrent response and electrochemical impedance spectroscopy (EIS) measurements corroborate Py–Thio–Tri CMP enhanced photogenerated carrier mobility and suppressed charge recombination dynamics.