To improve the photocatalytic performance, carbon nitride (C₃N₄) heterojunctions with carbon nanomaterials are being developed. Here, the electrostatic self-assembly method was used to create the GOQDs (graphene oxide quantum dots)/Hp-C₃N₄ (HNO₃ protonated carbon nitride) heterojunctions. Poor dispersion and weak interface bonding were addressed by using GOQDs, a derivative of graphene oxide (GO). The specific surface area of the GOQDs/Hp-C₃N₄ heterojunction increased from 7.445 m²/g to 33.634 m²/g, and the valence band potential increased from 2.016 eV to 2.367 eV. The GOQDs/Hp-C₃N₄ could generate higher levels of •OH and superoxide radicals (•O₂^-). The degradation efficiency of the heterojunction for pollutants (MO) under visible light was increased by 343, 9, and 4 times in comparison to C₃N₄, Hp-C₃N₄, and GO/Hp- C₃N₄, respectively. Our results showed that GOQDs derived from GO with smaller sizes and higher abundances of oxygen-containing functional groups make better co-catalysts for constructing heterojunctions with C₃N₄ to boost photocatalytic performance.