Purpose: To assess the effectiveness of different nonsurgical protocols for the treatment of peri-implant mucositis. Materials and methods: The identification of randomised clinical trials (RCTs) was systematically performed in three databases and supplemented by a thorough manual search of the literature in periodontics/implantology-related journals. Studies investigating the effect of mechanical and/or chemical plaque control agents aimed at preventing the development of peri-implant mucositis were excluded. When comparable trials were found, a meta-analysis was performed. Results: Fourteen studies were included in the systematic review and three in the meta-analysis. None of the selected studies reported a complete resolution of the peri-implant mucositis lesions. A nonsurgical therapy alone showed an average reduction of: 0.57 mm (95% CI [0.30 to 0.83]) in probing pocket depth (PPD); 22.41% (95% CI [12.74 to 32.08]) in bleeding on probing (BOP); 17.28% (95% CI [3.99 to 30.58]) in the plaque index (PI); and 13.41% (95% CI [3.50 to 23.31]) in the bleeding index (BI). The meta-analysis failed to demonstrate significant improvements with the adjunct use of chlorhexidine disinfectant to nonsurgical mechanical debridement for PPD reduction (–0.07 mm; 95% CI [–0.33 to 1.15], P = 0.62), and relative attachment level (RAL) gain (–0.13 mm; 95% CI [–0.6 to 0.35]), P = 0.6). Conclusion: Conventional nonsurgical mechanical therapy alone may be considered the standard treatment for peri-implant mucositis as there is still a lack of evidence supporting the use of additional chemical/mechanical agents for clinical and/or microbiological improvement.