Abstract This paper deals with the interaction of convection and thermal radiation on an unsteady magnetohydrodynamic (MHD) boundary layer flow of a viscous incompressible electrically conducting fluid past a rotating vertical plate whose temperature varies linearly with time. The fluid is considered to be a grey, absorbing–emitting but non-scattering medium, and the Cogley–Vincent–Gilles formulation is adopted to simulate the radiation component of heat transfer. An analytical solution of the governing equations has been obtained by employing the Laplace transform technique. The physical interpretation of the emerging parameters of interest on the velocity and temperature fields as well as shear stress and rate of heat transfer are shown through graphs and discussed in detail. It is found that the effect of the magnetic field is to decrease the velocity field. An increase in the values of rotation parameter suppresses the primary velocity and enhances the secondary velocity.