Sugarcane bagasse and sugar beet molasses represent the by-product materials, obtained following the processing of sugarcane and sugar beet, respectively. Both substrates comprise complex lignocellulosic carbon-containing compounds that can be used as low-cost energy sources for microbial growth and production of microbial metabolites under different fermentation conditions. Sugarcane bagasse and sugar beet molasses can be used as ideal substrates for microbial processes because of their plentiful availability. Improved substrate utilization often resulted from a pretreatment process by various microbes. Recently, the utilization of bagasse and beet molasses is gaining momentum as alternative substrates for the manufacture of high valued products such as enzymes, protein-enriched animal feed, amino acids, organic acids, and antibiotics. Several species of bacteria, yeast, and fungi grown on these low-cost substrates are famous for the production of antibiotics and enzymes. They offer many advantages over the traditional carbon sources. Moreover, the consumption of bagasse and beet molasses will tremendously enhance the productivity resources required for human sustainability. This review covers the industrial applications of bagasse and beet molasses with special reference to their potential significance as efficient substrates for the derivation of biochemicals.