This study examines the damage observed during the February 6, 2023, Kahramanmaraş earthquakes by the TAG (Tarsus–Adana–Gaziantep) Motorway viaducts which are in service for approximately 25 years in Nurdağı region together with their primary causes and a detailed evaluation of both the proposed and currently implemented retrofit methods. Although these viaducts were fully functional in a short period with the necessary emergency repairs after the February 6 earthquakes, a seismic retrofit was required to mitigate the risk of earthquake-induced damages during the remaining service life by meeting the requirements of the National Earthquake Specification. Since the structures remained standing during the February 6 earthquakes and the probability of being exposed to an earthquake of this magnitude during the remaining service life is low, seismic source modeling was performed to reduce spectral accelerations of 2475 years return period design spectrum. Thus, realistic and applicable retrofit scenarios were developed for the viaducts. Since karstic cavities are present, foundation jacketing and widening were performed together with steel micro piles. To increase ductility and strength of the circular columns with diameters of 3 m and 4 m, steel jacketing was applied, provided that its length is not shorter than the plastic hinge effective length. At places beyond the plastic hinge effective length and at secondary zones of columns, double and single layer bidirectional-fiber FRP wrapping were applied. By adding viscous dampers acting in longitudinal direction at the abutments, seismic demands were reduced. Retrofitting constructions are ongoing on site.