The transition towards low-carbon energy systems has been increasingly recognised as a critical global priority for mitigating climate change, reducing dependence on fossil resources, and promoting sustainable socioeconomic development. Although Brazil possesses one of the world’s most renewable energy matrices, supported primarily by hydropower, bioenergy, wind, and solar resources, significant challenges remain in the effective integration of waste-to-energy technologies and circular resource management strategies. In this review, the current status of renewable energy deployment in Brazil is critically assessed alongside the generation, management, and valorisation potential of major waste streams, including agricultural biomass, agro-industrial residues, food-processing wastes, municipal solid waste (MSW), wastewater sludge, construction and demolition waste (CDW), pulp and paper residues, and end-of-life tyres. Existing treatment practices and recovery technologies are systematically examined with emphasis on their capacity to convert waste into value-added products such as solid, liquid, and gaseous biofuels, secondary raw materials, and platform chemicals. Particular attention is given to technological limitations, regional disparities in infrastructure, and policy gaps that have constrained the broader implementation of decentralised renewable energy systems, especially in rural and residential sectors. It is observed that despite substantial progress in renewable electricity generation, waste recycling rates, energy recovery efficiency, and integrated waste management practices remain comparatively underdeveloped. The adoption of advanced thermochemical, biochemical, and material recovery technologies is shown to offer significant opportunities for emissions reduction, resource efficiency, and industrial symbiosis. Furthermore, the role of regulatory frameworks, economic incentives, and public investment in accelerating the transition towards a circular and low-carbon economy is highlighted. The findings demonstrate that the strategic integration of renewable energy expansion with waste valorisation could substantially enhance energy security, environmental performance, and economic resilience in Brazil. The technological pathways, policy mechanisms, and management strategies discussed are also considered transferable to other emerging economies facing similar energy and waste management challenges.