Mango (Mangifera indica L.) seed waste is an important by-product of fruit processing industry and a rich source of bioactive compounds with potential pharmaceutical applications. The present study was carried out to determine the phytochemical constituents and antimicrobial activity of mango seed and seed kernel extracts against selected bacterial and fungal pathogens. Phytochemical screening revealed the presence of some secondary metabolites such as phenolics, flavonoids, tannins, alkaloids and glycosides which are known for their antimicrobial properties. The antimicrobial activity was tested by agar well diffusion method against Staphylococcus aureus, Escherichia coli, Candida albicans and Aspergillus niger. The extracts showed concentration dependent antibacterial activity against S. aureus with maximum zone of inhibition was 16 mm at 10,000 µg and no inhibitory activity was observed for E. coli. Antifungal testing showed moderate activity against C. albicans with maximum zone of inhibition of 15mm at the highest concentration tested. No activity was detected against A. niger. S. aureus and C. albicans showed a higher susceptibility, which could be related to the effect of phenolic and flavonoid compounds present in the extracts. The results indicate that mango seed waste is a potential source of natural antimicrobial agents, which can be utilised in pharmaceutical, nutraceutical and food preservation applications as a sustainable source.