Raj Kumar (40), a resident of Moti Nagar, was arrested by a team of Delhi Police's Crime Branch near Ghazipur flyover on National Highway-24, Joint Commissioner of Police (Crime) Ravindra Yadav said.
One kg heroin was recovered from Kumar, he said, adding, that he had procured it from a Bareilly-based drug trafficker by the name Rabid.
During interrogation, Kumar said he himself was a drug addict and started supplying narcotics to meet the expenses of taking doses, police said.
An FIR has been registered in this connection at Crime Branch police station under NDPS Act provisions.
Kumar has been been convicted in a murder case and is out of jail currently as his appeal is pending in the High Court.