A dirty ex-Bronx cop yesterday pleaded guilty to trafficking cocaine and robbing a drug courier of hundreds of thousands of dollars.

Juan Acosta, 34, a married father of three, joined the NYPD in 2000.

Five years later, he began working with a friend, Yorick Rafael Corniel-Perez, to distribute coke around the city, according to Manhattan US Attorney Preet Bharara.

In one instance in 2005, Bharara said, Acosta used a marked NYPD car to rob a drug dealer.

The two were busted last December after Acosta made a deal with a purported Colombian drug lord to personally transport what he thought was a 10-kilogram shipment of cocaine from Long Island to The Bronx.

That deal was a sting, and the “drug lord” was an undercover informant.

The case against Corniel-Perez is pending.