Steven Blair was arrested in October after officers stopped his car in Hamilton, South Lanarkshire.
A £410,000 haul of cocaine was discovered - including a package of the class A drug.
The 28-year-old turned to crime after a failed football career. Blair was at the Ibrox club before signing for Newcastle United in 2002.
However, his career on Tyneside was not a success and he returned to Scotland to work as a scaffolder.
Blair faces a prison sentence after pleading guilty at the High Court in Glasgow to being concerned in the supply of cocaine.
Officers initially found one package in the car and Blair said: "That's coke, mate." A second parcel was discovered in the vehicle, on October 2, before Blair, of Castlemilk, Glasgow, was searched at a police station.
It was there he confessed he had more of the drug concealed in his underwear.
The court heard that it was accepted Blair had been acting only as a courier.
Tony McGlennan, defending, said Blair had been of "good character", but got into debt due to gambling.
Judge Lord Burns remanded the first offender, and deferred sentencing for reports.