OBJECTIVES: Photobiomodulation (PBM) is a laser-based therapy used to promote tissue repair, reduce inflammation and pain, and has been extensively studied in chemo- and radiotherapy-induced oral mucositis (OM). This review examines the level of evidence of systematic reviews (SRs) that have investigated PBM in such cases of OM. MATERIALS AND METHODS: SRs evaluating PBM for both the treatment and prevention of OM in patients undergoing chemotherapy and/or radiotherapy and published before November 30, 2023, on PubMed, Cochrane, Embase, Web of Science, LILACS, TRIP and Open Grey databases were eligible for inclusion. We assessed the level of methodological and meta-analytic procedures. RESULTS: Of the 1201 SRs, 21 that met the inclusion criteria were included. The quality of evidence was assessed using the Assessing the Measurement Tool to Assess Systematic Reviews (AMSTAR2), and the majority was of critically low quality (n = 15, 71.4%) with only 28.5% of low quality. A total of 40 meta-analytic estimates were obtained and analyzed. Approximately 87.5% of the meta-analysis were significant (n = 33), but only one meta-analyses had a strength of "highly suggestive", while the rest were classified as "weak". When analyzing the overlap values, the covered area was 12.14% and the corrected covered area was 7.75%, indicating a moderate overlap. Only 4 SRs had a very high overlap and one had a high overlap. CONCLUSION: The efficacy of PBM in the treatment of chemotherapy-induced OM is supported by low to critically low quality SRs and meta-analysis of low strength. This review highlights important areas that need to be addressed in future research on this topic. REGISTRATION: CRD42023484013 (PROSPERO).