<p>Repairing damaged reinforced concrete (RC) structures to restore their load-bearing capacity and extend their service life remains a critical challenge in civil engineering. Achieving efficient repair is essential for minimizing losses of life and property while maintaining structural stability. This study proposes a active confinement method for repairing damaged concrete columns using nickel-titanium shape memory alloy (Ni–Ti SMA) strips. A series of uniaxial compression tests were conducted to systematically investigate the effectiveness of SMA strip confinement in restoring the performance of damaged concrete columns. The influence of three key parameters-the number of SMA strips, pre-strain level, and degree of pre-damage on the failure behavior of the columns was analyzed in detail. Experimental results indicate that increasing the number of SMA strips and enhancing the prestress level can significantly improve both the compressive strength and deformation capacity of the repaired concrete columns. The crack closure rate achieved by the confinement provided by the SMA strips ranged from 5 to 35.7%, and the peak stress of the specimens increased by up to 45.44%. Based on the test results, a stress–strain constitutive model applicable to SMA-repaired damaged concrete columns was developed. The model’s calculated results show good agreement with the experimental data and demonstrate satisfactory generality and potential applicability. Overall, the findings of this study provide valuable theoretical and practical insights for rehabilitating damaged reinforced concrete structures.</p>