Heinsia crinita; a common vegetable in the south-eastern part of Nigeria with the local name “Atama” have been used as a component of various herbal portions in ethnomedicine. The plant part has been previously used in the treatment of umbilical hernia and skin rashes. There is dearth of information on the scientific rationale behind the use of this plant. This study was designed to investigate the pharmacological potentials of aqueous extracts of Heinsia crinita for the management/prevention of hypertension. Fresh, matured green leaves of Heinsia crinita were harvested from a local farm in Cross River State, Nigeria. The total phenol, total flavonoids, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability and ability of the extract to chelate Fe2+ as well as inhibition of Fe2+-induced lipid peroxidation in rat penile homogenate arginase and angiotensin-1-converting enzyme inhibitory activity were assessed. The results revealed that the extract had high total phenol and total flavonoid content. The extract also exhibited inhibitory effect on Arginase (EC50 = 3.93 mg/mL) and angiotensin-1-converting enzyme (ACE) (EC50 = 0.77 mg/mL). Furthermore, the extract exhibited strong antioxidant capacity as typified by DPPH scavenging and Fe2+ chelating abilities coupled with the inhibition of Fe2+-induced lipid peroxidation in rat penile homogenate in vitro. The bioactive constituents with beneficial medicinal properties coupled with the antioxidant activities and its inhibitory effect on key enzymes linked with hypertension may be the mechanism by which the extract manage and/or prevent hypertension and other cardiovascular diseases.