Herein, form-stable phase change material fibrous composite containing nanoparticles was prepared via a single-step green approach using single-nozzle electrospinning for the first time. Polyethylene glycol (PEG), polyvinyl alcohol (PVA), and water were used as PCM, polymeric support and safe solvent together with simultaneous formation of nanoparticles. The introduced manner not only is free from applying organic solvents, separate addition, or buying nanoparticles and coaxial electrospinning but also it is easy and cost-effective to use for different applications. Thermal energy storage capacity of the fabricated samples reached to 135.88 and 136.27 J/g in melting process for the nanofibers and nanofibers with nanoparticles, respectively, which are mostly higher than the reported works. Meanwhile supercooling temperature was decreased for (50% PVA/50% PEG/0.1% AgNO₃/1% TiO₂) nanofibers compared to the other fabricated composites and the pure PEG. The effects of different weight ratio of polymers in spinning solutions, amount of titanium dioxide nanoparticles and silver nitrate, range of phase change transition and thermal endurance and stability of the samples were further discussed in details. Altogether, this renders a single-step safe route for producing form-stable PCM nanofibrous composites and also a broad insight concerning the thermal behavior of such composites for diverse renewable energy applications.