Purpose: To assess whether adjunctive treatment modalities offer therapeutic advantages when used in combination with peri-implant debridement—defined as supra- and/or submarginal debridement using manual, sonic, and/or ultrasonic instrumentation—for the treatment of peri-implant mucositis. Materials and Methods: Relevant articles published in English between January 1980 and October 2023 were searched. Clinical trials involving ≥ 10 patients diagnosed with peri-implant mucositis and treated with debridement alone versus debridement plus an adjunctive treatment were included. Data were extracted and meta-analyses were performed to investigate the effect of different therapeutic approaches on several outcomes of interest (ie, pocket depth [PD] and bleeding on probing [BoP] reduction as well as complete disease resolution). Results: A total of 25 articles were selected, of which 19 were included in the meta-analyses. Peri-implant debridement generally resulted in PD and BoP reduction. For studies including nonsmokers or patients with unclear smoking status, outcomes of individual studies revealed that the use of certain probiotics, such as Lactobacillus reuteri strains, may modestly reduce BoP in the short term. For studies exclusively involving smokers or users of vapes/ electronic cigarettes, the clinical benefits of adjunctive therapy were negligible. Complete disease resolution was not consistently achieved regardless of the treatment modality. Conclusions: Peri-implant debridement as a monotherapy for the treatment of peri-implant mucositis generally results in clinical improvements in terms of PD and BoP reduction. The use of adjunctive treatment modalities does not appear to provide a clinically significant additional therapeutic benefit compared to debridement alone, independent of the patient’s smoking status. Complete peri-implant mucositis resolution is an elusive outcome.