Stanley introduced in 1986 the order polytope and the chain polytope for a given finite poset. These polytopes contain much information about the poset and have given rise to important examples in polyhedral geometry. In 1993, Reiner introduced signed posets as natural type-B analogues of posets. We define and study signed order and chain polytopes. Our results include convex-hull and halfspace descriptions, unimodular triangulations, Ehrhart $h^*$-polynomials and their relations to signed permutation statistics, and a Gorenstein characterization of signed order and chain polytopes.