Taraxacum farinosum and Taraxacum mirabile are endemic species traditionally used to treat diabetes. This study investigated the antidiabetic, antioxidant, and phytochemical properties of methanol extracts of aerial and root parts of both species and sub-extracts (n-hexane, dichloromethane, ethyl acetate, n-butanol, and water) derived from the active T. farinosum methanol extract. Enzyme inhibition assays revealed that the methanol extract (TFA) and ethyl acetate sub-extract (TFAEA) of T. farinosum showed superior α-amylase inhibition compared to the standard drug acarbose. In contrast, moderate inhibition was observed against α-glucosidase. The same extracts also demonstrated high total phenolic and flavonoid contents and exhibited vigorous radical scavenging activity in DPPH, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and FRAP assays. In cell line studies, the extracts showed a noncytotoxic effect at 1000 µg/mL on β-TC6 cell proliferation and enhanced insulin secretion in a glucose concentration-dependent manner (0–25 mM). LC–HRMS analysis identified ferulic acid as the major compound, along with luteoloside and liquiritigenin, which may contribute to the observed bioactivities. These results suggest that T. farinosum possesses multifaceted antidiabetic potential through enzyme inhibition, β-cell stimulation, and antioxidant mechanisms, supporting its traditional use and highlighting its potential for further pharmacological development.