The present research investigates the influence of ZrO2 nanoparticles on the microstructural, mechanical, and tribological behavior of magnesium matrix composites fabricated through ultrasonic-assisted stir-casting process. Microscopic characterization reveals the successful inclusion of ZrO2 nano-particles through several characterization methods like energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and optical microscopy. The effect of varying ZrO2 content (0.5, 1, 1.5, and 2 wt%) on the tribological behaviour is explored using a pin-on-disk wear tester. Wear experiments have been conducted under dry sliding conditions at different operating loads (10, 20, 30, and 40 N) and sliding velocities (0.1, 0.2, 0.3, and 0.4 m/s) at room temperature. The incorporation of ZrO2 nano-particles improves the micro-hardness of the cast base alloy and significantly enhances wear resistance. Additionally, an attempt has been made to identify the dominant wear mechanisms by analyzing the worn surfaces.