Amaranth is a rediscovered pseudocereal with high nutritional properties. Lactic acid fermentation can increase the functional and nutritional value of foods. The aims of this study were to isolate and evaluate the functionality of lactic acid bacteria (LAB) from amaranth. LAB strains (n = 29) isolated from amaranth sourdough and grains included Lactobacillus (L.) plantarum (n = 8), L. rhamnosus (n = 6), Enterococcus (E.) mundtii (n = 4), E. hermanniensis (n = 3), E. durans (n = 1), Enterococcus sp. (n = 1), Leuconostoc (Lc.) mesenteroides (n = 3), and Lc. mesenteroides subsp. mesenteroides (n = 3). Only 21% of the strains showed the ability to synthesize capsular exopolysaccharides or display ropiness and only 8 strains showed amylolytic activity. L. plantarum CRL 2106 and E. durans CRL 2122 showed the highest phytase activity, which is of importance for mineral bioavailability. L. plantarum CRL 2106 and CRL 2107 and Lc. mesenteroides subsp. mesenteroides CRL 2131 synthesized the highest concentrations of B₂ and B₉ vitamin (140-250 ng/mL). This study demonstrates the potential of LAB to improve the nutritional and functional values of pseudocereal-derived foods.