In the present study, to optimize the media for the production of bioactive compounds from Monochaetia karstenii was carried out and compounds were identified by GC-MS. M. karstenii was identified from infected Camellia japonica leaves by classical and molecular taxonomy. It was cultured in different media and determined their mycelial biomass and antibacterial activity. Further Maltose Maltose tartrate broth (MTB) was altered for its media components such as carbon, nitrogen, minerals, amino acids and vitamins sources and physical parameters like temperature, pH and incubation periods for growth and production of secondary metabolites from M. karstenii. The antimicrobial and antioxidant compounds were performed from three different solvent extracts (Chloroform, Dichloromethane and Ethyl acetate) of M. karstenii from optimized medium. M. karstenii had optimum growth in MTB showing mycelial growth of 13.16 g/L.  The ethyl acetate extract observed significant antibacterial activity against Escherichia coli (21 mm), Staphylococcus aureus (20 mm) and Vibrio chloreae (18 mm). In-vitro antioxidant activity revealed that, the IC₅₀ values for 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and total antioxidant radical scavenging assay of 100.58 μg/ml, 140 μg/ml and 141.91 μg/ml from ethyl acetate extract respectively. Thus the antimicrobial and antioxidant activity of the fungal extract has been due to the presence of biocompounds such as cyclohexenone derivatives, cinnamic acid, isooxazoline 3-phenyl- benzodiazepine, 2- propenoic acid 3-phenyl-(E)-dodecene and 3-undecen -1-yne (E) were characterized by gas chromatography-mass spectrometry (GC–MS) and reported first time in M. karstenii. We conclude that M. karstenii possess excellent antimicrobial and antioxidant potential and can be exploited for the discovery of new drug molecules.