Four electronic databases (MEDLINE via Pubmed; EMBASE via Ovid; EBSCO Dentistry and Oral Science Source), in addition to six related journals (Clinical Implant Dentistry and Related Research; Clinical Oral Implants Research; International Journal of Oral and Maxillofacial Implants; International Journal of Oral Implantology; Journal of Clinical Periodontology; Journal of Periodontology), were searched for publications until 2022. Randomised controlled trials (RCTs), evaluating the effectiveness of local or systemic antibiotics as an adjunct in the non-surgical treatment (NST) for peri-implantitis (PI), were assessed. The eligibility criteria included RCTs with a parallel group, split-mouth design and appropriate NST interventions over a three to twelve month period. Data were extracted from RCTs to capture a multitude of primary outcomes, including: implant success rate, radiographic marginal bone loss rate, periodontal health changes and PI resolution. Risk of bias assessments were made using the Cochrane Collaboration's tool, by two authors independently and in duplicate. RCTs with similar observation periods and interventions were included in the meta-analyses. Random-effects meta-analyses of mean differences or relative risks with 95% confidence intervals were calculated, in additional to data heterogeneity calibration through I2 statistics. Following the screening of 270 papers, six RCTs were included, which resulted in the evaluation of 391 patients (375 implants). Adjunctive local antibiotic therapy at disease sites showed statistically significant periodontal outcomes; improvements in success rate (risk ratio = 9.89; 95% CI 2.39-40.84), probing pocket depth (mean difference (MD) = 0.6 mm; 95% CI 0.42-0.78) and bleeding on probing (MD = 0.15%; 95% CI 0.10-0.19). Conversely, adjunctive systemic antibiotics improved probing pocket depths (MD = 1.15 mm; 95% CI 0.31-1.99) and probing attachment levels only (MD = 1.10 mm; 95% CI 0.13-2.08). Across the six included RCTs, the bone loss rate and PI resolution rate determined no significant differences between the groups; mirrored in the single studies and in the meta-analysis. Disease resolution ranged from 2 to 65%. Two of the studies were found to be at low risk of bias and four presented with some concerns. Adjunctive antibiotics aid NST. However, the heterogeneity of study methods and low quality of current RCTs evidenced, deem their role in NSTs of PI as inconclusive.