This study presents a new fractional differential equation model for cancer virotherapy that uses the generalized Hattaf fractional (GHF) derivative with a non-singular kernel. The paper rigorously investigates the existence and uniqueness of solutions within this model, providing a fundamental understanding of its mathematical posedness. A comprehensive stability analysis of the model’s equilibrium points has been performed using the GHF derivative to elucidate its dynamical behavior. The results are presented through detailed numerical simulations, which not only validate the theoretical findings but also provide insights into the practical applications of the model in cancer virotherapy.