In this paper, we study particle transport and deposition in a turbulent square duct flow with an imposed magnetic field using direct numerical simulations (DNS) of the continuous flow and Lagrangian tracking of particles. The magnetic field and the velocity induce a current and the interaction of this current with the magnetic field generates a Lorentz force that brakes the flow and modifies the flow structure. A second-order accurate finite volume method is used to integrate the coupled Navier–Stokes and magnetohydrodynamic (MHD) equations and the solution procedure is implemented on a graphics processing unit (GPU). Magnetically nonconducting particles of different Stokes numbers are continuously injected at random locations in the inlet cross section of the duct and their rates of deposition on the duct walls are studied with and without a magnetic field. Because of the modified instantaneous turbulent flow structures as a result of the magnetic field, the deposition rates and patterns on the walls perpendicular to the magnetic field are lower than those on the walls parallel to the magnetic field.