Police say Juan Moxthe crashed into a guardrail about 2:30 a.m. Dec. 17, in the 12100-block of West Irving Park Road near O'Hare airport in Bensenville.
His vehicle, with three other family members inside, flipped over several times.
Jaylene Escamilla, 28, of Addison was thrown from the vehicle, and died.
The two other people in the car, a 50-year-old woman, Moxthe's wife, and a 30-year-old man, Escamilla's husband, were treated by paramedics at the scene, police said.
Moxthe, seriously injured in the crash, was initially taken to a hospital.
Moxthe was allegedly driving with a 0.12 BAC level, which is over the legal limit of 0.08, authorities said.
They had been drinking at a Rosemont bar to celebrate Escamilla's birthday. Escamilla would have turned 29 the next day, ABC7 Chicago news partner the Daily Herald reported.
Moxthe pleaded guilty to aggravated DUI causing death.
He could be sentenced to probation or up to 14 years in prison. He remains free on pretrial release while awaiting sentencing.
He's next due in court Nov. 13.