Samuel George Davis Jr. was born on December 8, 1925 in New York City, New York to Sammy Davis Sr. and Elvera Sanchez. He was their only child. Both his parents were vaudeville performers. His parents separated when he was three and his father gained custody of him.
His father worked for a dance troupe led by Will Mastin and Sammy joined them as a child artist. The three of them performed together as the Will Mastin Trio.
He enlisted in the U. S. Army during the World War II. There he experienced racial discrimination for the first time in his life.