The aim of this article was to study the effect of symmetrical as well as asymmetrical tilt grain boundaries on the tensile deformation of irradiated bicrystalline zirconium. Molecular statics-based simulations were performed to generate both types of tilt grain boundaries with [0001] and as the tilt axis. Effect of irradiation-induced point defects was studied with respect to deformation mechanism and changes in grain boundary structure of these bicrystals using molecular dynamic simulations. Twinning, formation of dislocation networks and shift in grain boundaries were predicted as the main deformation mechanism. In most of the cases, irradiation-induced defects strain-harden the material. Spatial distribution as well as the number of point defects plays a critical role in the strain hardening of the material subjected to tensile deformation. In grain boundary structures formed with [0001] as the tilt axis, the twinning and dislocation loops formed with irradiation-induced defects govern the deformation mechanism of bicrystalline Zr, whereas in as the tilt axis, dislocation networks and dislocation density govern the tensile properties in the bicrystals. It can be concluded from the atomistic simulations that structure of grain boundary governs the deformation mechanism of bicrystalline Zr in conjunction with the irradiation-induced defects.