The present study investigates the antioxidant, α-glucosidases, and anti-inflammatory properties of leaf extract of Cassia singueana and C. sieberiana. Cassia singueana and C. sieberiana are restorative plants utilised for the treatment of diabetes, ulcer, malaria, and wound healing. The extracts were evaluated for antioxidant activities via DPPH radical scavenging, ABTS+ radical cation scavenging, FRAP, β-carotene bleaching, phenolic content, and flavonoid content. Meanwhile, α-glucosidases and anti-inflammatory properties were also evaluated against α-glucosidase enzyme and 15-LOX inhibitory activities. The results for C. singueana extract revealed potent activities for DPPH (IC50: 9.35 µg/mL), phenolic contents (120.01 mg GAE/g dry extract), and α-glucosidases inhibition (I%: 90.47%). On the other hand, the findings for C. sieberiana recorded significant activities for FRAP (2120 µmol Fe2+/g dry extract) and 15-LOX inhibition (I%: 80.93%). The extract of C. singueana and C. sieberiana contain possible antioxidant, α-glucosidases, and anti-inflammatory agents that are responsible for the popular use of these plants in the treatment of diabetes and ulcer.