One of the main goals of retrofitting reinforced concrete (RC) structures is to enhance their safety against natural disasters like earthquakes. A significant number of RC buildings in Canada were constructed several decades ago and may be vulnerable to earthquakes due to the absence of modern design considerations. Therefore, seismic retrofitting of RC buildings is essential to minimize earthquake damage. This study compares two of the most popular techniques used for retrofitting such structures. A six-story RC building located in a high-seismicity zone is retrofitted using a base isolator and a tuned mass damper. The retrofitting systems are designed using routine methods, and their ability to reduce earthquake damage is evaluated. Buildings upgraded with two different retrofitting systems are modeled in the OpenSees software package and subjected to several seismic events. According to the results, the routine methods used for designing the optimal linear TMD and base isolation may not be sufficient to ensure highly efficient performance, as their effectiveness depends on the intensity of seismic excitation.