This research considers the impact of a point/line heat source/sink on steady magnetohydrodynamic (MHD) natural convection flows in a vertical channel subjected to a transverse magnetic field with a thermal boundary condition of the third-kind thermal (Robin) boundary conditions. A constant point/line heat source/sink generates convection current within the flow. The governing dimensional equations regulating the physical situation at hand are presented in dimensionless form with the associated boundary conditions. Exact solutions are derived for the momentum and energy equations using the Laplace transform technique. The effects of key controlling parameters involved in flow formations are studied, such as the magnetic parameter, point/line heat source/sink parameter and Biot number on flow behaviour are analyzed. MATLAB software is employed to obtain line graphical and tabular results. The findings indicate that lower values of the Biot number account for reduced heat transfer to the surroundings, whilst higher values lead to higher surface heat transfer. Furthermore, the heat transfer rate, frictional drag force and mass flow rate retard as the line heat source/sink approaches a point heat source. In addition, the mass flow rate increases by almost 49% as the interval between the line heat source increases. for both equal and unequal values of the Biot number. There is remarkable agreement between the current results and the previously published studies.