A significant rim defect encountered during revision surgery can make stable cementless cup fixation difficult. One approach to this problem is to medialize the acetabular cup to improve the degree of rim contact. In this study, we investigate this technique, termed the medial protrusio technique, for acetabular fixation in revision hip arthroplasty. A retrospective review of 25 patients (25 hips) who underwent medialization was performed. Clinical and radiographic evaluation was performed. At an average follow-up of 6.6 years, the overall patient function and satisfaction were good to excellent, with a mean Harris hip score of 85.2. This demonstrates that the medial protrusio technique can be a valuable option in addressing acetabular cup failure.