Heterotopic ossification (HO) is a common complication after total hip arthroplasty (THA) and can result in pain and loss of motion of the hip. This is the first study in the literature to determine if a short course of Celecoxib is effective in the prevention of HO in patients undergoing cementless THA. In this retrospective study of prospectively collected data, consecutive patients undergoing a primary cementless THA were reviewed at a 2-year follow-up. The Control group consisted of 104 hips that did not receive Celecoxib (Control group), while the 208 hips in the Celecoxib group received 100 mg twice daily for 10 days. Radiographs, patient-recorded outcome measures and range of motion (ROM) were evaluated. Overall, there was a significantly decreased incidence of HO in the Celecoxib group (18.7%) than in the Control group (31.7%) (p = 0.01). The odds that a patient developed HO using Celecoxib were 0.4965 times the odds that a patient developed HO without treatment. Clinically, the Celecoxib group demonstrated significantly greater improvement in their mean WOMAC stiffness (0.35 vs. 0.17, p = 0.02) and physical function scores (3.26 vs. 1.83, p = 0.03) compared to those in the Control group, but there was no difference in the ROM between the two groups. This study is the first to demonstrate that the lowest dose of Celecoxib for a short course of only 10 days is a simple and effective prophylactic treatment option that can significantly reduce the incidence of HO following cementless THA.