BACKGROUND: The effectiveness of intra-articular platelet-rich plasma (IA-PRP) injections for managing pain in knee osteoarthritis (KOA) remains inconsistent. Therefore, this study aimed to systematically review randomized controlled trials (RCTs) assessing the efficacy of IA-PRP. METHODS: A total of 21 studies meeting the inclusion criteria were selected from various scientific databases, all of which compared PRP to either a placebo or an active comparator, such as corticosteroids (CS), in the treatment of KOA. Weighted mean differences (WMDs) for the Visual Analogue Scale (VAS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Knee Injury and Osteoarthritis Outcome Score (KOOS), along with their 95 % confidence intervals (CIs), were calculated for each study. A subgroup analysis was conducted for the pain scores, comparing leukocyte-poor and leukocyte-rich PRP with either a placebo or CS. The evidence was synthesized using a random-effects meta-analysis. RESULTS: There were 2406 participants in all included studies; 1223 were in the PRP versus placebo group and 1183 were in the PRP versus corticosteroid group. The IA-PRP showed significant improvement of VAS, and WOMAC scores compared to placebo (P < 0.00.05), except KOOS score (P > 0.05). All pain scores were highly sinficant improved with IA-PRP, compared to IA-CS (P < 0.05). Additionally, the leukocyte rich PRP was efficasious than leukocyte poor PRP (P < 0.05) improving the all pain scores at the 6-month follow-up. CONCLUSIONS: PRP treatment showed better results than placebo and corticosteroids in terms of reducing pain and improving function in KOA patients. Furthermore, lecocyte rich PRP is more effective than lecocyte poor PRP [PROSPERO, CRD42024540507].