"During a check of passengers from a plane from Bogota, the gestures and behaviour of a supposed tourist raised the suspicions of narcotics agents," they said in a statement.
After a baggage search revealed nothing, female officers conducted a body search of the 43-year-old woman and discovered "certain irregularities and deformations in both breasts".
At that moment, the suspect started to act nervously and "confessed that she was carrying implants with cocaine inside," the statement said.
The woman was taken to a hospital where the implants were removed and found to contain 1.7 kilos (3.74 pounds) of the drug.
Although unusual, it is not the first time Spanish police have seen drug smugglers using breast implants to try to beat detection.
In December 2012, a Panamanian woman arriving in Barcelona from Bogota was found with 1.4 kilos of cocaine in her fake breasts. Her recent insertion wounds were still bleeding under bandages.
Other techniques have included drugs hidden under wigs, mixed into a cast put on a leg, and shaped and hardened into crockery.
Spain has a special police unit that checks "hot flights" from major drug-trafficking countries.
So far this year, in Madrid airport alone, the squad has seized around 500 kilos of cocaine and six kilos of heroin, and had made 189 arrests.