We accomplish the complete two-loop computation of the leading-twist contribution to the photon-pion transition form factor γγ^{*}→π^{0} by applying the hard-collinear factorization theorem together with modern multiloop techniques. The resulting predictions for the form factor indicate that the two-loop perturbative correction is numerically important. We also demonstrate that our results will play a key role in disentangling various models of the twist-two pion distribution amplitude thanks to the envisaged precision at Belle II.