We report the effect of topological as well as lattice vacancy defects on the electro-thermal transport properties of the metallic zigzag graphene nano ribbons at their ballistic limit. We employ the density function theory–Non equilibrium green’s function combination to calculate the transmission details. We then present an elaborated study considering the variation in the electrical current and the heat current transport with the change in temperature as well as the voltage gradient across the nano ribbons. The comparative analysis shows, that in the case of topological defects, such as the Stone-Wales defect, the electrical current transport is minimum. Besides, for the voltage gradient of 0.5 Volt and the temperature gradient of 300 K, the heat current transport reduces by $${sim }62,\%$$∼62\% and $${sim }50,\%$$∼50\% for the cases of Stones-Wales defect and lattice vacancy defect respectively, compared to that of the perfect one. © 2014, Springer Science+Business Media New York.