Endophytic fungi have attracted considerable attention because of their diverse bioactive compounds and potential pharmaceutical applications. In this study, we investigated the antioxidant activity of endophytic fungi isolated from green and brown algae. The isolates were obtained from various algal species, and their antioxidant potential was assessed using standard assays. The DPPH assay and reducing power assay were used to measure the antioxidant properties of fungal strains (Fug 03-07) against a specific biochemical process. The inhibitory potential of these strains was assessed using optical density (OD) at 517 nm and compared to the control group. Fug 05 consistently displayed the strongest inhibitory effect across all concentrations, suggesting its most potent influence on the process. Ascorbic acid mirrored these low OD values, confirming its inhibitory efficacy. Fug 09 displayed the highest percentage inhibition at lower concentrations, while Fug 07 emerged as the leader at higher concentrations. The observed concentration-dependent trend suggests that the inhibitory effects of fungal strains strengthen with increasing concentration, highlighting their potential for various applications. The strong inhibitory effect of ascorbic acid aligns with its known antioxidant properties. Further research is needed to understand the underlying mechanisms and explore potential applications. The results indicate that these endophytic fungi possess significant antioxidant properties, making them promising candidates for further research in the field of natural antioxidants.