Leong was born in Shanghai, and he moved to the United States with his parents when he was young.

[1] He graduated from Marion Normal College in Muncie, Indiana, in 1915[2] and briefly worked at a newspaper before moving to Hollywood, where he worked at first as a technical director for filmmakers like D. W. Griffith and Wesley Ruggles.

[1][3][4] By 1919, he had started his own production company — James B. Leong Productions, later known as the Wah Ming Motion Picture Company — to show Chinese life as it really was.

[5] He had grown tired of seeing Chinese people portrayed as kidnappers and assassins on the screen.

[6] Under this banner, he wrote and directed the 1921 film Lotus Blossom.