Introduction:Metformin is an antihyperglycemic medication most commonly used to treat Type II Diabetes Mellitus with promising off-label application for the treatment of hidradenitis suppurativa, psoriasis, acne, acanthosis nigricans, and hirsutism. Objective: To comprehensively assess evidence regarding the use of metformin for treating primary cutaneous disorders. Materials and Methods: A systematic literature search was conducted through PubMed, Cochrane, Web of Science, and CINAHL to identify the role of metformin in primary skin disease. Results: Sixty-four studies met inclusion criteria. Metformin demonstrates promising clinical response and favorable safety profile for treatment of HS, with most patients experiencing a decrease in frequency or severity of HS flares, and some experiencing full resolution of HS lesions. Patients with psoriasis treated with metformin experienced quantifiable clinical responses. Application of metformin on polycystic ovarian disease (PCOS) related acne, acanthosis nigricans, and hirsutism yielded mixed clinical results. No serious adverse effects were reported. Conclusion: Metformin is safe and efficacious and may be considered as an adjunctive therapy for the treatment of psoriasis and hidradenitis suppurativa in addition to first line therapies as well as PCOS related acne, acanthosis nigricans, and hirsutism. J Drugs Dermatol. 2020;19(8): doi:10.36849/JDD.2020.4874.