In this study, forced convection heat transfer for flow past a square cylinder in a channel with both the cylinder and channel being heated has been analyzed by lattice Boltzmann method. The study details the effects of Reynolds number and blockage ratio on forced convective flow and heat transfer characteristics of a heated channel in presence of a heat generating square cylinder. Channels with a heat source are of interest in many technological processes such as electronic cooling, heat exchangers, and nuclear reactors. The thermal management and control of these geometrical configurations are sometimes meager with the help of natural convection; as such forced convection is enforced. The present work focuses on the behavior of the streamlines, isotherms, coefficient of drag, coefficient of lift, and the Average Nusselt number for different combinations of controlling parameters. The results pointed that the enhancement of heat transfer rate is generated principally with decreasing diameter of the obstacle and obstacle placed at the end of the channel.