Herbal remedies and medicinal plants have long been valuable natural resources for pharmaceutical, cosmetic, and perfumery industries. Endophytic fungi, which live symbiotically within plants, offer potential therapeutic benefits. The objective of this study was to isolate and characterize endophytic fungal species from the leaves of Mammea suriga Buch.-Ham. ex Roxb., an evergreen tree endemic to the Western Ghats of India. Leaves were collected, surface-sterilized, and cultured on various agar media to isolate endophytic fungi. The cultured fungal strains were subjected for morphological and molecular identification, which resulted in two fungal isolates: Phyllosticta capitalensis (BGMSB-01) and Diaporthe pseudophoenicicola (BGMSW-01). The extracts of both fungal isolates showed significant inhibition against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The zones of inhibition indicated that D. pseudophoenicicola (BGMSW-01) has stronger inhibition (3.79 ± 1.48 mm and 2.39 ± 0.67 mm, respectively) compared to P. capitalensis (BGMSB-01) (inhibition zones of 1.2 ± 0.52 mm and 1.72 ± 0.18 mm, respectively). Plant Growth-Promoting (PGP) activity was evaluated using Phaseolus lunatus seeds, where isolate BGMSB-01 completely inhibited the germination, while BGMSW-01 showed significant increase in germination and seedling growth promotion.