Abstract: In the present invention, a method of producing a colourant-incorporated silk fibroin is provided. In a preferred embodiment, the method comprises the steps of: i) decrystallizing a degummed silk fibroin in the presence of an acidic solution or a metal salt solution (i.e. lithium bromide); ii) mixing one or more colourants with the decrystallized silk fibroin and iii) recrystallizing the decrystallized silk fibroin containing the colourants such that it forms a recrystallized region encapsulating the colourants, thereby obtaining the colourant-incorporated silk fibroin. In addition, a cosmetic product comprising the colourant-incorporated silk fibroin is provided.