This study aims to develop a new type of multifunctional phase change microcapsules (MPCM) suitable for the field of building materials, featuring both heat storage and radiation resistance capabilities. MPCM was prepared using a self-assembly method, and the introduction of barium with a high atomic number into its shell endowed MPCM with additional anti-ionizing radiation properties. This study comprehensively evaluated the chemical structure, phase change properties, thermal stability, and radiation shielding effectiveness of MPCM in cementitious materials. Experimental results showed that the prepared MPCM exhibited an ovoid or spheroidal shape, and its core-shell structure was physically interconnected, effectively maintaining the heat storage density of the phase change core material. The phase change temperature and latent heat of MPCM were 4.79°C and 101.13J/g, respectively, demonstrating good thermal stability. After 80 thermal cycles, the phase change temperature remained unchanged, and the latent heat decreased by only 5.23 J/g. Furthermore, MPCM was added to cement slurry. When incorporated into the cement slurry, the resulting MCP blocks exhibited significantly enhanced radiation shielding effects at lower photon energies. The linear attenuation coefficient of MCP10% blocks increased by 42.2% compared to the control group. This indicates that the addition of MPCM significantly enhanced the anti-ionizing radiation capability of cement materials, paving a new path for improving the performance of building materials. In summary, this study not only successfully prepared MPCM with excellent heat storage and radiation resistance properties but also expanded its potential applications in the field of building materials, providing a new approach to manufacturing building materials with enhanced environmental adaptability and energy efficiency.