This paper performs Direct Numerical Simulation of transition induced by blowing and suction in a spatially evolving Mach 2.25 supersonic boundary layer. We use a novel algorithm (Park & Mahesh 2007) capable of solving compressible flow on unstructured grids. Our objective is to evaluate our unstructured capability to simulate supersonic transition. Transition is achieved using controlled periodic fluctuations over a region of the wall. It is observed that the applied perturbation produces streamwise vortices which breakdown to produce a turbulent boundary layer. The results of the turbulent region are compared to available data and a good agreement is obtained. The transition process is highly unsteady and localized, and the paper presents the sensitivity of the transition location to the streamwise mesh resolution.