The global textile industry releases nearly 280,000 tons of synthetic dyes each year, generating persistent pollutants that disrupt aquatic ecosystems and pose carcinogenic and mutagenic risks. Conventional treatment technologies such as activated carbon adsorption, advanced oxidation processes, and biological degradation often fail to address the complexity of real industrial effluents. This review critically evaluates engineered biochar metal oxide nanocomposites (BMO-NCs) as emerging dual-functional materials that integrate adsorption with photocatalytic degradation for targeted dye removal. We highlight how the tunable surface chemistry, hierarchical porosity, and electronic conductivity of biochar synergize with metal-oxide-driven reactive oxygen species (•OH, •O₂⁻, h⁺) to enhance degradation pathways. While laboratory studies frequently report >95% dye removal, real-wastewater conditions such as fluctuating pH, high salinity, and competing contaminants significantly reduce performance. To bridge this gap, we identify key research priorities, including mechanistic validation of ROS via in-situ ESR, LC-MS tracking of degradation intermediates, long-term regeneration and metal-leaching assessments, and standardized testing protocols for industrial effluents. This review provides design principles for scalable, safe, and circular-economy-aligned BMO-NCs, underscoring their potential contribution to Sustainable Development Goal 6.).