This paper reports a new class of efficient, green and metal-free visible-light photocatalyst made from graphene aerogel (GA) doped with a conjugated porous polymer (CMPs). Hence, we report the synthesis of a benzothiadiazole (BTZ)-based CMP loaded into GA via a one-step hydrothermal reaction between 2D graphene oxide (GO) and the CMP, performed through a green process and under mild conditions. The as-prepared GA showed a bathochromic shift in the UV-vis diffraction reflectance spectroscopy (DRS) absorption edge to 628.5 nm, demonstrating its ability to absorb light in the visible region. SEM, TEM, XPS, EDX mapping results further showed the successful loading of the BTZ-based CMP in the GA array. The synthesized GA was used as a 3D structured photocatalyst for the visible-light-driven photodecomposition of methyl orange (MO) with an efficiency of 89.2% (5 wt% CMP). When compared to that of the pure CMP (86.9%), a comparable yet small increase in the efficiency was observed. This is due to a synergistic effect between GO and loaded polymer in GA array upon the formation of CMPGA hybrid structure via chemical interaction between BTZ-Py and GO throughout the mild hydrothermal reaction, and the enhanced photocatalytic activity exhibited from 1 mg equivalent polymer in the CMPGA2 hybrid when compared to the 20 mg pure polymer. Upon repeated use, the depreciation in photocatalytic activity was low with a < 5% drop over 3 cycles. These results showed the CMP-loaded GA as an efficient metal-free photocatalyst and a promising material for further investigation into other photocatalytic applications.