Investigators say 33-year-old Cody Welch, of Tulsa, was drinking Saturday before he crashed his truck in Fort Gibson.
Officers say Welch also had marijuana in his pickup.
Welch’s 5-year-old son was ejected from the pickup and later died in a Tulsa hospital.
Investigators say the boy was not wearing a seatbelt.
On Tuesday, the father was charged with second-degree murder.
This case makes Welch’s third DUI.
Welch now faces 10 years to life in prison.
The suspect is also charged with possession of marijuana and failure to maintain a security verification form for having no insurance.
Welch is scheduled to be in court March 26 for a preliminary hearing.