This study demonstrates the development of thermal energy storage cementitious composites (TESCs) by integrating a form-stable phase change material (PCM) composite into cement matrix. The PCM composite was fabricated on paraffin and hydrophobic expanded perlite. The mass percentage of paraffin in the composite can reach as much as 50% due to the excellent absorption capacity of expanded perlite. Fourier transform infrared (FT-IR) spectroscopy and thermo-gravimetric analysis (TGA) tests show that the fabricated PCM composite has good chemical compatibility and thermal stability. TESCs developed by partially replacing the fine aggregate with PCM composite reveals that the composite PCM has good compatibility with cement matrix. It is shown that TESC developed with 60% substitution level of composite PCM resulted in 28-day compressive strength of 25 M.P a. Furthermore, compared to ordinary cement mortar, maximum reductions on 28-day compressive strength, apparent density and thermal conductivity with the 80% substitution level.are 70%, 48% and 66% respectively. The thermal performance test shows that thermal energy storage capacity of TESC with 80% substitution level is increased by 166% compared to ordinary cement mortar. Furthermore, mechanical and thermal reliability tests reveal that the TESCs do not show any signs of degradation when subjected to 1000 accelerated thermal cycles.