In this research, different techniques of repair of deficient reinforced concrete columns are compared. These include carbon fiber–reinforced polymer sheets, steel jackets, and reinforced concrete jackets. The experimental investigation includes testing of 16 deficient columns of dimensions 150 × 150 × 800 mm subjected to concentric and eccentric loading up to failure. Two main variables are considered: the load eccentricity and the strengthening technique. The experimental results showed that the three strengthening techniques used in this research significantly improved the ultimate load carrying capacity in all cases of loading. Also, in the two cases of concentric loading and big eccentricity of 150 mm, carbon fiber–reinforced polymer wrapping achieved the highest ductility and absorbed energy capacity. In addition, strengthening with reinforced concrete jacket improved the initial stiffness and toughness. The cracking load, ultimate load, and ductility of the deficient columns after strengthening were experimentally recorded and compared. The results can help the structural engineer to consider the most efficient method of repair for such columns.