The fourth-order $\ensuremath{\pi}\ensuremath{-}\ensuremath{\pi}$ scattering resulting from nonlinear pion-pion couplings is investigated to show how such couplings can be regularized by the method of auxiliary fields. Special care is required in the choice of coupling terms involving the auxiliary fields to ensure that all quartic divergences are canceled by the $\ensuremath{\delta}(0)$ terms in the regularized effective interaction. It is found that four counterterms are necessary for the elimination of divergences in the process under consideration. In the limiting case of massless pions, the $\ensuremath{\pi}\ensuremath{-}\ensuremath{\pi}$ scattering result is free from infrared divergence, satisfies Adler's condition, and requires only two counterterms for renormalization.