Consumers have increasingly favoured fermented drinks due to their high content of probiotic secondary metabolites. These beverages are believed to possess the capacity to safeguard against non-communicable ailments such as coronary heart disease, cancer, diabetes, antimicrobial infections, and other dietary-related disorders. Lemongrass () is a commonly used botanical ingredient in therapeutic tea production. It is renowned for its highly valuable essential oil, which has significant commercial demand. This study examines the functional content and antioxidant effects of fermented beverages derived from lemongrass. We employed the yeast to carry out the fermentation process on the lemongrass compositions, extending the duration from t = 24 to t = 96 h. We used non-fermented samples as control. This investigation identified numerous active biomolecules and polyphenols in the fermented samples, including flavonoids, tannins, cardiac glycosides, coumarins, terpenoids, steroids, saponins, and reducing sugars. After t = 24 h fermentation, the radical-scavenging activity reached its maximum level of 89.1%, and the antioxidant content reached 13.06 µg/ml, which is equivalent to the amount of ascorbic acid. After t = 36 h fermentation, the total phenolic content reached a concentration of 237.19 µg/ml, while the flavonoid content reached its peak at 55.21 µg/ml after t = 72 h fermentation. Lemongrass fermentation exhibits a wide range of phytochemicals and bioactive components that effectively eliminate free radicals, despite the antioxidant content fluctuation throughout the fermentation period of t = 24 to t = 96 h.