Melanoma is a highly malignant skin cancer worldwide and it is more dangerous than other types of skin cancers because of its rapid and distant metastasis ability when not diagnosed and treated at an early stage. Tyrosinase, an enzyme that is a crucial biomarker of melanoma, is an important hotspot in research on melanoma. Herein a tyrosinase-activated cyclometalated Pt(II) complex (Pt-tyro) for melanoma photodynamic therapy (PDT) and fluorescence imaging was proposed for the first time, which was used in-vivo and in-vitro. Pt-tyro is under the specific activation via tyrosinase and rapidly rearranged and eliminated as fluorescent Pt-OH, which exhibits a higher phototoxicity and efficiently induces melanoma cell apoptosis. The prodrug Pt-tyro has the potential for use in displays imaging and photodynamic therapy in the A375 cell murine xenograft tumour model. Based on these findings, we suggest that the strategy combining imaging and treatment within a single fluorophore, may provide a reference for cancer theranostics.