Background: The direct superior approach (DSA), a muscle-sparing technique derived from the posterior approach (PA), has received little attention despite its potential advantages. This study compared the impact of the DSA and PA on patient-reported pain and postoperative opioid consumption with medical and surgical complications. Methods: We reviewed 451 primary total hip arthroplasties for osteonecrosis of the femoral head and osteoarthritis between January 2016 and December 2022, which were categorized as DSA or PA. Demographic data, including age, sex, preoperative opioid usage, smoking status, chronic alcoholism, and underlying diseases, were collected. Propensity score matching balanced the DSA and PA groups. The maximum and minimum pain score on the postoperative day (POD) and total opioid consumption were compared between the two groups. Inflammation-related serum markers, medical and surgical complications, and the length of hospital stay were also analyzed. Results: After matching, 139 patients were included in each group. Patients with the DSA reported a lower average maximum pain on POD #1 and #4 and a lower average minimum pain on POD #1, #2, and #4. The DSA group showed a significant reduction in opioid consumption. In addition, the DSA led to a significant reduction in C-reactive protein (CRP) on POD #5, 14, and 28 after the index surgery compared to the PA. Postoperative delirium (3.6 vs. 9.4%, p = 0.05) and length of stay (5.4 vs. 8.4 days, p < 0.001) were significantly different between the two groups. No significant differences were observed in chronic opioid use, medical complications, or other surgical complications. Conclusions: The DSA was associated with lower patient-reported pain and a marked reduction in opioid consumption, delirium, and length of hospital stay.