Veronica (Plantaginaceae) and Schoenoplectus have a unique chemotaxonomic and phytochemical importance and are widely utilized in Turkish and Traditional Chinese Herbal Medicine (TCM) for treating tonics, influenza, diuretics, expectorants, restoratives, and respiratory diseases, and both are very useful in treating infectious and metabolic disorders as well. This study evaluates two medicinal plant species, Veronica biloba and Schoenoplectus triqueter (L.) Palla; extraction was performed through Soxhlet and maceration methods as well as determination of free and bound phenolics. Evaluated biological screening of (extracts and phenolics) angiotensin-I converting enzyme (ACE), Type-II diabetes (α-glucosidase and α-amylase), and antioxidants potential was performed using modified assays. The angiotensin-I converting enzyme (ACE) 50% inhibition potential in Veronica biloba was found at IC50 = 210.68 μg/mL and in Schoenoplectus triqueter (L.) Palla at IC50 = 229.40 µg/mL, respectively. Meanwhile Type-II diabetes with α-amylase 50% inhibition shown by bound phenolics of Veronica biloba at IC50 = 219.66 µg/mL and its water extract at IC50 = 110.09 µg/mL possesses higher potential, and α-glucosidase potential by free phenolics was found to be active at IC50 = 469.56 µg/mL, while water and ethyl acetate extracts showed higher potential, IC50 = 78.65 µg/mL and IC50 = 97.03 µg/mL, than the standard acarbose, recorded lower. In case of amylase, α-glucosidase showed IC50 = 88.73 μg/mL. Our results showed that both plants possess a direct relationship with the increase in the concentration of extracts and inhibited very strongly angiotensin-I converting enzyme (ACE) and Type-II diabetes (α-glucosidase and α-amylase). The properties of enzyme hindrance may be associated with phenolic compounds and rich phenolic plant antioxidant potential provides a route to the elucidation of natural antihypertension and antidiabetes.