The urgent global transition towards renewable energy has positioned biodiesel as a pivotal alternative for decarbonizing industrial sector. Moving beyond the contentious “food-versus-fuel” dilemma of first-generation biofuels, this review focuses on the sustainable production of biodiesel from non-food biomass, including agricultural residues, non-edible oilseed crops (e.g., Jatropha curcas and Pongamia pinnata), waste streams, and microalgae. The chapter provides a systematic analysis of the entire value chain, beginning with a classification of biofuel generations and a critique of food-based feedstocks’ socio-economic and environmental limitations. It then details the typology of advanced non-food feedstocks and the technological evolution in conversion processes, highlighting breakthroughs in heterogeneous catalysis and microwave-assisted and ultrasonic transesterification that enhance efficiency and sustainability. The analysis further addresses critical technological and environmental challenges, such as feedstock variability and emission profiles.