In order to explore the effectiveness of microwave ablation at 2.45 GHz on irregularly shaped tumors, Fe₃O₄ nanoparticles were used to generate hotspots and to investigate enhanced microwave ablation in specific areas of biomimetic phantoms. Fe₃O₄ nanoparticles were synthesized using a chemical co-precipitation method and were characterized using transmission electron microscopy and a Zeta potential analyzer. Theoretical analysis indicated that adding a nano heat source term into the biological heat transfer equation for microwave ablation can significantly enhance heat generation. 5 mL phantom in a culture dish was heated, and a significant improvement in microwave heating was observed due to the presence of nanoparticles, as verified by infrared thermography. Additionally, Fe₃O₄ nanoparticles were uniformly and selectively added in a 100 mL thermochromic biomimetic phantom, and temperature changes at equidistant points within the phantom were measured experimentally during microwave ablation. The results show that uniformly doping Fe₃O₄ nanoparticles throughout the phantom ensures that the temperature distribution remains axially symmetric, and these nanoparticles are effective in reducing microwave power and shortening heating time. Furthermore, when Fe₃O₄ nanoparticles are locally injected into the phantom, the maximum temperature difference at equidistant points inside the phantom reaches 27.7 ℃, enabling selective microwave ablation of the phantom. It is concluded that local injection of Fe₃O₄ nanoparticles enables selective enhanced microwave ablation at specific points in the phantom. This approach helps prevent central carbonization and excessive damage to the surrounding tissues, which is a reference for conformal microwave ablation in irregularly shaped tumors.