Nicholson ya fara zuwa Hollywood a 1954, lokacin da yake da shekara goma sha bakwai, don ziyarci 'yar'uwarsa. Ya ɗauki aiki a matsayin ma'aikacin ofishin don masu zane-zane William Hanna da Joseph Barbera a gidan wasan kwaikwayo na MGM. Sun ba shi aikin farawa a matsayin mai zane-zane, amma ya ƙi, yana mai cewa yana so ya zama dan wasan kwaikwayo. Ya horar da shi a matsayin dan wasan kwaikwayo tare da ƙungiyar da ake kira Players Ring Theater, bayan wannan lokacin ya sami ƙananan sassa da ke aiki a kan mataki da kuma TV soap operas. Ya fara fim dinsa a cikin wani matashi mai suna Cry Baby Killer (1958), yana taka rawa.
Mai kashe jariri mai kuka (1958)