Research on highway alignment optimization has been quite intensive over the last two decades. Determining the best candidate for highway alignment is one of the most complex highway design stages due to the different effects of various parameters. Hence, in the present study, Analytic Hierarchy Process technique and Geographic Information System are proposed to determine the best highway candidate with special focus on the constraint, cost and safety criteria. The methodology presented in the current research is not limited to the constraint, cost and safety criteria but can be extended to other criteria. This methodology has been implemented on a case study region in northwestern of Iran, and therefore the constraint, cost and safety criteria have been obtained for the case study conditions. The final result of the current paper indicates that the optimal highway candidate obtained with the proposed methodology can concurrently satisfy all relative parameters in highway alignment optimization based on their impact.