Cu2O nanoparticles were directly formed on the boron carbonitride (BCN) sheets by thermal condensation technique. Photocatalytic hydrogen evolution efficiency was greatly influenced by three-dimensional distribution and loading of Cu2O in the nanocomposite network structure. The oxidation state, crystalline phase, and size of the supported/un-supported nanoparticles were observed by XPS and XRD, and the internal morphology was determined via HR-TEM analysis. Visible light response and band position was confirmed by measuring the diffuse reflection spectroscopy (DRS). An efficient thermal, combined with a condensation method, was used to synthesize these nanocomposite architectures, which were then embedded into the BCN network. The broad visible light absorption of the synthesised nanocomposites was influenced by Cu2O loading on BCN sheets. The red shift in UV spectra of BCN/Cu2O confirmed that presence of Cu2O on BCN sheets resulted in reduced bandgap compared with the wider bandgap in BCN sheets. The H2 evolution activity was 59 μmol/h for the prepared composites, which is 59.5% enhanced compared with bare BCN. The enhanced photocatalytic activity was due to the influence of Cu2O on the BCN surface and enhanced charge separation in the interface at Cu2O with BCN.