The acetone contained in human breath is of great interest for the health sector as it is a marker that allows to diagnose and control diabetes in a non-invasive way. However, its concentration is extremely low. Therefore, high-performance acetone sensors are still a challenge. With this in mind, MgCo₂O₄ nanoparticles were synthesized using a microwave-assisted colloidal route with subsequent calcination. Structural and morphological characterizations were done through various techniques. The MgCo₂O₄ sensor was fabricated with the sample calcined at 500 °C. The sensing results showed that the sensor could detect acetone vapors ranging from 0.5 to 50 ppm at an optimum operating temperature of 250 °C with a high response, repeatability, stability, and selectivity. These sensing characteristics revealed that MgCo₂O₄ could be used as a new sensor material to detect acetone in exhaled human breath.