During the evolution of civilization, humans generated the food from farming. Since then, his food habits including nutritional necessities have changed. Today, consumptive manners are highly diversified and cause several diseases and spoil the natural immune characteristics. Out of this background, this chapter delivers about the ‘bacterial single cell proteins their applications, productions and commercialization’. Naturally, single cell proteins are a refined or purified form of protein derived from microorganisms used by substrates under artificial conditions. They are the richest sources of proteins, vitamins, and minerals. There is numerous bacterial spp., such as Acinetobacter calcoaceticus, Achromobacter delvaevate, Aeromonas hydrophila, Bacillus subtilis, B. megaterium, Brevibacterium spp., Cellulomonas spp., Flavobacterium spp., Lactobacillus spp., Methanotrophic spp., Pseudomonas fluorescens, and Rhodopseudomonas capsulate. Bacterial SCPs are produced through semi-solid fermentation with continuous process of cell disruption, removal of nucleic acids, washing, purification, and drying. In addition to bacteria, fungi, algae, and yeasts nutritional supplements like Quorn™ (Fusarium venenatum) and Pekilo (Paecilomyces variotii) are used by global corporations. It is a growing science-based industry. Furthermore, growth of SCPs depends upon food habits and demand, and in future, it will play a dominant role in human food and health care.