Let \((M, g, \omega , f, \lambda )\) be a Kähler gradient Ricci soliton in real dimension four. The first theorem states that it is an integrable Hamiltonian system in a classical sense. Furthermore, either it is of cohomogeneity one or the integrals of motion are given by the potential function f and the scalar curvature \({\mathrm S}\) . The second theorem states that if the system is non-degenerate and f is proper, then there is an effective, completely integrable Hamiltonian \(\mathbb {T}^2\) - action.