Objective: To identify and describe unusual soft tissue complications of periodontal plastic surgery procedures at the recipient site after periodontal grafts. Materials and methods: Two independent reviewers performed a comprehensive search in MEDLINE, Cochrane, periodontics journals, reference lists, and grey literature for articles dated up to July 2021. Publications related to surgical interventions only around the teeth with an unusual complication at the recipient site were selected. No restrictions were made in the number of cases, follow-up period, or language. The Cochrane Collaboration’s tool for assessing risk of bias, the Newcastle–Ottawa Scale (NOS), and two validated case report/series checklists were used to critically appraise the studies. Results: A total of 1434 articles were examined, of which 28 met the inclusion criteria: one RCT, two cohort studies, and twenty-five case reports/series. The periodontal plastic surgery procedures described in these articles were conducted to treat lack of attached gingiva and gingival recessions. The following unusual complications were found: bone exostosis, epithelial inclusion, root resorption, abscess, overgrowth, “liver clot” formation, and oroantral communication. Conclusion: Bone exostosis and epithelial inclusions were the most prevalent unusual complications following treatment with subepithelial connective tissue graft, free gingival graft, and acellular dermal matrix allograft. Due to the nature of the reports, the clinical recommendations for diagnosis and treatment cannot be homogenized. Clinical studies reporting complications are required to develop management protocols (PROSPERO CRD42021230875). Clinical relevance: Clinicians need to know the main complications that can occur in mucogingival surgeries as well as their clinical management to provide a successful and predictable treatment.