The relationship between mucosal human papillomavirus (HPV) and cervical carcinoma or anogenital squamous cell carcinoma (SCC) is becoming increasingly evident, whereas a link between HPV and other cutaneous SCCs is less clear. Recent studies have reported links between epidermodysplasia-verruciformis-associated HPV and extragenital cutaneous SCC, particularly in immunosuppressed patients, although immunocompetent patients have also been affected. Mucosal HPV could also be linked to some types of Bowen disease and certain SCCs of the fingers, oropharyngeal mucosa, etc. We review the possible oncogenic mechanisms involving mucosal HPV and epidermodysplasia-verruciformis-associated HPV. Most SCCs could be explained by the combined action of HPV, immunosuppression, and the oncogenic and immunosuppressive effect of UV radiation. HPV might be associated with worse prognosis of SCC, with implications for clinical practice including greater risk of metastasis.