The impact of fermentation assisted by four different lactic acid bacteria (LAB) on polyphenols, carotenoids, organic acids, and antioxidant capacity of orange-juice milk based beverages was evaluated. Lactobacillus brevis POM, and Lactobacillus plantarum (TR-7, TR-71, TR-14) were used to promote the fermentation of the beverages for 72 h at 37 °C. The bacteria population increased with the elapse of fermentation period, except for beverages inoculated with L. plantarum TR-7. After fermentation period, total polyphenols, total carotenoids and total antioxidant capacity were increased compared to the control ones (non-fermented). Two phenolic acids (DL-3-phenylactic acid and 3-4-dihydroxyhydrocinnamic acid) and lactic acid were identified after 72 h fermentation. Overall, it is possible to conclude that orange-juice milk beverages are a good medium for the growth of L. brevis POM, and L. plantarum (TR-71, TR-14), observing higher antioxidant properties in the fermented beverages compared to the control ones.