Phase change materials (PCMs) have demonstrated tremendous potential in emerging thermal management. However, developing PCMs with miniature size and reliable thermal management capability towards the temperature control of miniature electronic components still remains challenging. In this work, granulation of phase change material gel particles (PCMGPs) is proposed as a novel strategy of processing the pristine PCMs, which is conducted by a facile two-step of PCM droplet formation and sol-gel transition. The obtained PCMGPs demonstrate micron size suitable for microelectronic components. The boron nitride (BN) hybridization in the PCMGPs can further enhance their thermophysical properties. The PCMGPs possess a high phase transition enthalpy of 139.01 J g−1, high thermal conductivity of 0.9739 W m−1 K−1 (175 % improvement) and high form stability (no leakage). Owing to the merits of size matching, reliable heat storage and enhanced heat transfer, the PCMGPs are packaged in a smart phone to regulate the thermal environment of the CPU under various working conditions. Results reveal that PCMGPs can significantly decrease the working temperatures of CPU and prevent the thermal shock under high operating load. The working temperatures of CPU can be decreased by 5.4 °C and 8 °C under low and high operating loads, respectively. It can be predicted that this micromachining method has a pioneering guiding significance in the field of micro-scale PCM preparation and micro-scale heat conduction.