The aim of this research is to look at the social identity formation of Don Shirley as presented in Green Book (2018) movie. The research applies a qualitative descriptive approach in collecting and analyzing the data. The primary data were taken from Green Book using purposive sampling. The finding of the observation is discussed using semiotics theory to understand how the Social Identity Formation of Don Shirley is portrayed in Green Book movie. This research also applies Social Identity Theory to analyze the formation of social identity from the character Don Shirley. The result of this research shows that through his three social identity formation aspects, Don Shirley finds a harmony between his upper class and African-American identity.