Background Jaundea pinnata (JP), is a new plant native to North Africa, East Africa, Southern Nigeria, and Guinea. It is traditionally used as an anti-rheumatic, anti-inflammatory, antibacterial and antidiabetic herb, thus making it a potential source for modern antidiabetic medications. Objective This investigation aimed to assess the toxicological profile and the antidiabetic potentials of the methanol extract of the Jaundea pinnata (JP) leaf in mice and rats. Methods Preliminary phytochemical screening of JP leaf was conducted using standard procedures. The plant extract's acute and sub-chronic toxicity was evaluated using a modified OECD recommendation. In normal and streptozotocin-induced diabetic rats, its anti-diabetic action was tested over 28 days at doses of 100 mg/kg, 200 mg/kg, and 400 mg/kg, with glibenclamide (10 mg/kg) and distilled water serving as the positive and negative controls, respectively. Relevant organs' histopathological analysis was also assessed. Results According to the preliminary phytochemical analysis of the leaf extract, JP contains flavonoids, saponins, alkaloids, tannins, terpenoids, deoxy-sugars, and anthraquinones. The extract demonstrated an LD50 of above 2000 mg/kg in mice. On days 14, 21, and 28 in streptozotocin-induced diabetic rats, the extract showed a dose-dependent antidiabetic effect; nevertheless, the activity of the extract at 400 mg/kg on day 28 was barely comparable to that of glibenclamide (10 mg/kg). At 250 mg/kg, 500 mg/kg, and 1500 mg/kg, respectively, the extract was appreciably non-toxic to the liver and kidney, while inducing a significant change in haematological indicators. Conclusion The study found that JP presented antihyperglycemic properties and was relatively safe at normal dosages (< 2000 mg/kg).