This article deals with the application of the Chebyshev collocation spectral method (CSM) to the analysis of thermal radiation effects on magnetohydrodynamics free convection in a square cavity. The improved projection scheme, which is based on the spectral methods, is applied to treat the coupling of the velocity and the pressure. The radiative transfer equation is angularly discretized by discrete ordinates method with an SRAP_N quadrature scheme, and then solved by CSM using the same grid system as in solving the flow field. Streamlines, isotherms, and Nusselt number are analyzed for the effects of various parameters, such as inclination angle of the magnetic field, Hartmann number, optical thickness, and scatter albedo.