Som and Krystin Lisaius's four-month-old daughter had ingested the drug through breast milk, the court heard.
She was taken to Oro Valley Hospital on May 15 after she became unresponsive and her eyes 'were rolling into the back of the head' after breast feeding.
The pair did not want to allow the hospital to draw the baby's blood, so they left against the hospital's recommendation, but agreed to have her transferred to another facility.
Officials transported the baby girl via ambulance to Diamond Children's Hospital, and once there, the couple was still uncooperative and refused a toxicology test for the child.
Eventually, a urinalysis and a toxicology screen that was conducted in the presence of hospital staff along with officials with child welfare.
The tests showed that the baby girl had cocaine in her system. But the 26-year-old mother first denied using cocaine and said she didn't know how the baby was exposed to it.
She then admitted to police that she snorted cocaine with her husband on May 14 while hosting friends in their Oro Valley home, according to a police report obtained by the Arizona Daily Star.
Police obtained a search warrant and found 1.59 grams of cocaine and a scale inside their home on May 16.
The former Tuscon TV presenters face up to two years in prison for the offence which happened the morning after the couple had hosted a party. The baby has been in the care of her grandmother since the ordeal.
The Arizona celebrities had been charged with three felonies each, including child abuse, possession of narcotics and possession of drug paraphernalia.
But if the judge accepts the plea then the other charges will be dropped.