In addition to the great biodiversity of flora and fauna, Mexico has a wide cultural diversity with more than fifty ethnic groups, which include the Mayans in the Yucatan peninsula. Presently, many species of the Yucatecan flora are consumed by the people living in the Yucatan peninsula, as part of their everyday diet. However, to date, little is known about the health benefits of these species and the bioactive secondary metabolites responsible for these effects. This investigation evaluated the antioxidant, antidiabetic, anticancer, and anti-AGEs activities, as well as the phytochemical composition, of fifteen fruits and one plant traditionally consumed in the Yucatan peninsula, to explore their potential as functional foods. The results showed that the high antioxidant activity of the fruits of Byrsonima bucidifolia Standl, Melicoccus bijugatus (Jacq) and Phyllantus acidus (L) Skeels positively correlated with their total polyphenol content. Alternatively, testing of all the extracts for their potential antidiabetic activity showed that only the fruits of Cucurbita moschata (Duchesne ex Lam.) and Cordia dodecandra (A.DC.) significantly inhibited the α-glucosidase activity. Finally, UPLC-MS analyses allowed the identification of a number of polyphenols, including quercetin, phenolic acids, and epicatechin, in the different extracts. Given that functional foods demonstrate beneficial biological functions beyond basic nutrients, the results of this investigation suggest that the fruits of Byrsonima bucidifolia Standl, M. bijugatus (Jacq), C. moschata (Duchesne ex Lam.) and C. dodecandra (A.DC.) could be considered as potential functional foods because of their antioxidant capacity and potential antidiabetic properties.