This study investigates the anti-inflammatory properties of Hydrocotyle bonariensis Comm. Ex Lam, a medicinal plant used by indigenous traditional healers to manage chronic inflammatory diseases especially rheumatism and arthritis. The hexane extract of H. bonariensis leaves was evaluated for the presence and concentration of phytochemicals. It was subjected to heat-induced albumin denaturation and human red blood cell (HRBC) membrane stabilization assays. The anti-inflammatory properties of the extract were further assessed by employing the formaldehyde induced arthritis animal model assay. The extract was finally subjected to GC/MS analysis for the tentative identification of the phytochemical constituents. Phytochemical analysis of the extract revealed the presence of saponin, phenol, flavonoid, tannin, terpenoid and sterol. This extract showed the ability to inhibit thermally-induced protein denaturation and stabilize HRBC membrane in concentration dependent manner. In the formaldehyde induced arthritis model, the paw measurements of the rats were taken, their hematological parameters were determined, and their liver function tests (aspartate aminotransferase and alanine aminotransferase activities) were also carried out. Results from the animal model indicated that oral administration of the hexane extract of H. bonariensis leaf at a dose of 250 mg/kg body weight had potent anti-inflammatory action. The GC/MS analysis suggested a number of anti-inflammatory compounds in the extract among which were: hexadecanoic acid methyl ester, falcarinol and phytol. Consequently, the tentative identification of phytochemicals with anti-inflammatory activity in H. bonariensis affirms the anti-inflammatory property of the plant and the phytochemicals could serve as lead compounds for designing anti-inflammatory drugs.