Functional foods offer health benefits that extend beyond basic nutrition, addressing critical public health challenges such as diabetes and hypertension. This study developed a novel lactic acid bacteria (LAB)-fermented beverage integrating sea buckthorn and monk fruit, two bioactive-rich ingredients with complementary properties. Sea buckthorn provides a robust profile of antioxidants, while monk fruit's natural sweetness and low glycemic index make it an ideal ingredient for health-conscious consumers. Three LAB strains (Lactiplantibacillus plantarum (LP), Lacticaseibacillus paracasei (LPC), and Lactobacillus acidophilus (LA) were utilized individually and in combination to evaluate their impact on the beverage's bioactive and functional properties. Phenolic profiling (HPLC) revealed 13 phenolic compounds, with LPC fermentation achieving the highest total polyphenol content (232.50 ± 2.37