This meta-analysis compared the efficacy of platelet-rich plasma (PRP) injections with corticosteroids (CS) in the treatment of adhesive capsulitis based on 13 randomized controlled trials with 1056 patients (531 in the PRP group, 525 in the CS group). Primary outcomes were VAS pain score and DASH functional score, secondary range of motion (ROM) in abduction, flexion, external and internal rotation. No statistically significant differences were found in VAS and DASH scores at 1 month, VAS at 3 months or in flexion ROM. However, the PRP group showed significantly better results in VAS scores at 6 months (MD: −1.84, 95% CI: −2.57 to −1.10, p < 0.00001), DASH at 3 months (MD: −5.88, 95% CI: −9.72 to −3.03, p = 0.0008) and at 6 months (MD: −14.42, 95% CI: −9.72 to −3.03, p = 0.0008). 95% CI: -16.35 to -12.49, p < 0.00001), as well as in abduction (MD: 11.90, 95% CI: 2.23 to 21.57, p = 0.02), external rotation (MD: 5.35, 95% CI: 0.02 to 15.39, p = 0.02) and internal rotation (MD: 10.04, 95% CI: 8.80 to 11.29, p < 0.00001). Thus, PRP provided benefits in long-term pain relief, functional improvement, and range of motion at 6 months, while both treatments were comparable at short-term follow-up up to 3 months.