This study investigated the structural performance of corroded reinforced concrete (RC) columns strengthened with a carbon fiber-reinforced polymer (CFRP) composite under axial eccentric loading. The effects of the volumetric ratio of the confinement on the post-rehabilitation performance of columns with different corrosion degradation levels under eccentricity were investigated by testing 12 square RC columns. The experimental results indicated that the CFRP jacket had a reduced confinement effect in columns with corrosion damage before the CFRP installation. The effectiveness of the strengthening system depended strongly on the volumetric CFRP ratio. At a relatively high volumetric CFRP ratio, the confinement effect was restored in severely corroded columns under eccentric loading. In addition, the ultimate load and ductility of the columns were significantly improved. Finally, the precision of an analytical and a mechanical property model for the capacity calculation of CFRP-confined columns with corrosion damage was evaluated.