Use of edible mushroom as nutritious food or feed supplementation is widespread. Here, we evaluated the nutritional quality of edible mushroom Pleurotus sajor-caju as a single cell protein (SCP) grown in supplemented whey medium. Crude protein content of the SCP was found to be 39.25 ± 3.89% of the dried biomass. Essential amino acids (EAAs) including high amount of lysine, leucine, threonine and phenylalanine were identified in the P. sajor-caju SCP. Three independent ‘scores’ were calculated based on EAA content to understand nutritive value of the SCP. The ash content of the SCP was high (16.2 ± 0.83%) with presence of major and trace minerals. The SCP contained both saturated and unsaturated fatty acids in its lipid and is an excellent source of polyunsaturated fatty acid, linoleic acid. High amounts of arabinose, mannose and N-acetylglucosamine were measured in the SCP while glucose and galactose contents were low. The SCP was found to be a rich source of B-vitamins. These results suggested P. sajor-caju SCP is a rich source of nutrition.