We derive a robust a posteriori error estimate for hp-adaptive discontinuous Galerkin discretizations of stationary convection–diffusion equations. We consider one-irregular meshes consisting of parallelograms. The estimate yields global upper and lower bounds of the errors measured in terms of the natural energy norm associated with the diffusion and a seminorm associated with the convection. The ratio of the constants in the upper and lower bounds is independent of the local mesh sizes and weakly dependent on the local polynomial degrees. Moreover, it is also independent of the magnitude of the Péclet number of the problem, and hence the estimate is fully robust for convection-dominated problems. We apply our estimator as an error indicator in an hp-adaptive refinement algorithm and illustrate its practical performance in a series of numerical examples.