Sami, 40, was driving on Sunset Boulevard in Los Angeles when he lost control of the car and swerved into oncoming traffic. He then hit another car, Daily Mail reports.
Hayek's as yet identified male passenger died at the scene, while Hayek was taken to the hospital with several broken ribs and facial lacerations.
The 20-year-old driver of the other car was also taken to the hospital with a broken foot and body pain.
What caused the accident is still under investigation.
Sami currently runs his own design studio in Los Angeles.
Sami Hayek, younger brother of actress Salma Hayek, was involved in a tragic car crash on Sunday that killed a passenger in his car.