The treatment of skin diseases has entered a new era, and several biologics have been approved to treat dermatosis. However, biologics are expensive and inconvenient to preserve and inject. Therefore, safe, effective, and inexpensive treatments have never stopped being developed. Metformin is the most commonly used drug in treating type 2 Diabetes Mellitus (DM), which has a wide range of pharmacological effects. In recent years, studies on metformin’s anti-inflammatory and anti-tumor effects have become more promising. Metformin is efficacious against inflammatory skin disorders such as psoriasis, acne, hidradenitis suppurativa, and allergic contact dermatitis. It also demonstrated anti-tumor properties in keratinocyte carcinoma and melanoma. In addition, metformin has displayed therapeutic efficacy in cutaneous disorders associated with endocrine, including hirsutism, acanthosis nigricans, and eruptive xanthomas. Finally, metformin is expected to contribute to the improvement of skin pigmentation, uvb-induced skin damage, alopecia and wound healing This paper presents a narrative review through PubMed to determine the role of metformin in skin diseases. We also offer an outlook on nanoparticles combined with conventional drugs such as metformin for precisely targeted therapy.