The novel pH-responsive polymer nanoparticles have been widely used for drug delivery and cancer therapy. The pH-sensitive nanoparticles include chemical structures that can accept or donate protons in response to an environmental pH change. Polybases which mostly contain alkaline groups such as amines and hydroxy, accept protons at low pH and are neutral at higher pH values. This study aimed to prepare pH-sensitive colloidal amphiphilic poly (vinyl alcohol-2-hydroxyethyl methacrylate)(PVA-PHEMA) copolymers in cancer therapy applications. For this purpose, poly (vinyl acetate-2-hydroxyethyl methacrylate)(PVAc-PHEMA) copolymer nanoparticles were synthesized in different polymerization medium fractions from water and methanol and different monomer feed concentration. Then acetate groups were hydrolyzed, and the PHEMA-PVA nanoparticles were synthesized. The nanoparticles were further characterized using dynamic light scattering, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis to identify the structural and morphological changes. The Methotrexate (MTX) was loaded into the nanoparticles, and drug release kinetics were evaluated. The results confirmed that PHEMA-PVA copolymeric nanoparticles could be favorably used in cancer therapy.