Navin Johnson heads to Los Angeles to attend the wedding of his pen pal, Marie. On the way, he runs across a gang of hobos whose leader, Diesel, takes him to Las Vegas after learning of his skills at poker.

The Jerk follows the story of Navin Johnson, a man who was adopted by a poor black family and grows up to be an extremely dumb and naive person. After leaving home and hitchhiking across the country, Navin finds himself in various absurd and comedic situations, eventually becoming a millionaire and losing it all.