The Crown Prosecution Service (CPS) announced yesterday it had authorised the Metropolitan Police to charge the former X Factor judge with "being concerned in" the supply of drugs.
The charge facing the 25-year-old relates to a newspaper investigation between early March and May 23 this year which "resulted in the supply of Class A drugs to an investigative journalist".
CPS London chief Crown prosecutor Baljit Ubhey said: "This decision to prosecute was taken in accordance with the code for Crown prosecutors. We have determined that there is sufficient evidence for a realistic prospect of conviction and that a prosecution is in the public interest."
Ms Contostavlos will be required to appear before Westminster Magistrates' Court on December 19.
A Scotland Yard spokesman said the singer had been charged alongside Michael Coombs, 35, of Enfield.