Food waste and its accumulation are becoming a critical problem worldwide as the population grows. Approximately 1.4 billion tons of food have been wasted worldwide. Due to weak infrastructure, cities in developing nations are wasting more food than those in developing nations, which poses serious threats to our society, including environmental pollution and health risks. There is an urgent need to take appropriate measures to reduce the burden of food waste by implementing standard management practices. A circular economy aims to give food waste a new life as it is the most preferred method for its proper disposal. Sugarcane bagasse and sugar beet molasses are by-product materials produced during the sugarcane and sugar beet processing process, respectively. Both substrates comprise complex ligno-cellulosic and starch-containing compounds that can be used as low-cost energy sources for microbial growth and metabolite production under various fermentation conditions. Pretreatment with various microbes frequently resulted in improved substrate utilization. Bagasse and beet molasses have recently gained attraction as alternative substrates for producing high-value products such as enzymes, protein-enriched animal feed, amino acids, organic acids, and antibiotics. They have numerous advantages over traditional carbon sources. Furthermore, consuming bagasse and beet molasses will significantly increase the productivity resources needed for human sustainability. This chapter discusses the valorization of bagasse and beet molasses, focusing on their potential value as efficient substrates for various biotechnological and industrial applications.