We establish a Dynkin formula and a Courrège-von Waldenfels theorem for sublinear Markov semigroups. In particular, we show that any sublinear operator A on C_c^∞(R^d) satisfying the positive maximum principle can be represented as supremum of a family of pseudo-differential operators: (Formula presented) As an immediate consequence, we obtain a representation formula for infinitesimal generators of sublinear Markov semigroups with a sufficiently rich domain. We give applications in the theory of non-linear Hamilton–Jacobi–Bellman equations and L´evy processes for sublinear expectations.