Thirty-two-year-old Erica Dawn Gindlesperger, of Johnstown, faces up to five-and-a-half years in prison when she returns to be sentenced by a Somerset County judge on Sept. 25.
Conemaugh Township police found the woman had traces of a cocaine metabolite and two anxiety medications in her bloodstream when she crashed on Nov. 27, 2010.
Gindlesperger's passenger, 34-year-old Matthew Kozak, died five days later of a brain injury.
Gindlesperger didn't comment after Tuesday's guilty pleas.
Police say she was driving at least 49 mph in a 35 mph zone and hit a utility pole and an embankment when rounding a curve on Route 403.