Robust right coprime factorization and robust stabilization of nonlinear feedback control systems are studied. The concept of robust right coprime factorization of nonlinear operators for feedback control systems is introduced. Some conditions for the robustness of a right coprime factorization of a nonlinear plant under unknown but bounded perturbations are derived. An example with a closed-form solution is included to illustrate the general theory and a step-by-step construction of the robust factorization and the robust stabilization.