<p>The escalating demand for sustainable energy and the urgent need to mitigate greenhouse gas emissions have brought increased attention to the valorization of residual biomass through thermal pretreatment and densification technologies. Residual biomass is a widely available, underutilized resource for renewable energy production. To improve its energy performance and overcome logistical and combustion challenges, thermal pretreatment via torrefaction, combined with densification into pellets or briquettes, has emerged as a promising pathway. This article reviews the integration of torrefaction and densification processes, with a particular focus on the potential of co-processing diverse biomass residues to produce high-quality solid biofuels. The challenges associated with densifying torrefied material, including reduced binding capacity and increased energy consumption, and how co-processing with blended biomass can mitigate these issues, are also elaborated. The interrelated effects of process parameters, including pressure, temperature, moisture content, and binder type, on the quality of biomass pellets and briquettes are also highlighted. The perspectives presented in this article suggest that co-densification technologies could yield new insights into the production of solid biofuels from blended heterogeneous feedstocks, thereby reducing carbon emissions and addressing concerns related to waste management and energy security.</p>