Mulberry leaf is the solo food and source of nutrition for the silkworm, Bombyx mori L. Fortification of mulberry leaves with supplementary compounds was found to increase the larval growth and post cocoon characteristics. Silk production is dependent on the larval nutrition and nutritive value of mulberry leaves. The use of commercial pre and probiotic bacteria in sericulture has tremendous scope. So to explore the effectiveness on nutritional and commercial characteristics of B.mori the study was carried out. Mulberry leaves supplemented with commercial pre and probiotics Flora-SB at the concentration of 1%, 3% and 5% were administered, starting with the first day, first feed of each instar. The research was performed with control and experimental groups of 3 replications of 50 larvae each. In order to have a detailed picture of the energy and economical parameters, daily measurement of dry matter ingested, faeces produced, biomass gained by the larvae, quantitative and qualitative characters of the cocoon were recorded. Pre and probiotics with a concentration of 3% was very effective and recorded maximum food consumption (1.836 ± 0.07g), assimilation (1.544 ± 0.05g), tissue growth (0.118 ± 0.002g), RGR (54.06 ± 1.84 per cent), cocoon weight (1.98 ± 0.09g), shell weight (0.37 ± 0.01g) and filament length (804.26 ± 23.12m). Probiotics are live microbial food supplement that beneficially affect an individual by improving intestinal microbial balance. Prebiotics are non- digestible dietary fiber that exert some biological effect by stimulating growth or bioactivity of beneficial microorganisms. Thus pre and probiotics together enhances nutritional efficacy of B.mori which inturn reflect on the quality improvement of cocoon characteristics.