The workers picked up the sofa on East 137th Street in the Port Morris section, and when they placed it in the back of the truck to be compacted, white powder was released, police said.
The workers called police, who determined that the powder was cocaine and found that the sofa contained about 370 pounds (170 kilos) of the drug with a street value of about $8 million.
It was unclear who put the drugs into the couch. No arrests were made, and police continued to investigate, said department spokesman Det. Gary Cillo.
Detective told the New York Post that it appeared the couch was dumped on the side of the road by a nearby truck rental company. An employee told police someone who had recently rented the truck returned it Friday, but left the sofa inside, the Post says. Not knowing what to do, the employee dumped the sofa on the street, the Post quotes police as saying.
Investigators are seeking the truck's renter, but don't believe he or she is the one who stashed the coke in the couch, the Post says, adding that detectives think the coke's owner either died or went to jail, and his apartment was cleaned out by a landlord or relative.