Kevin Sutherland, 46, was convicted by a jury in the State Supreme Court of attempted grand larceny in the second degree and faces up to seven years in prison when sentenced on May 19.
The pastor, who dabbles in art dealing, came a cropper after approaching auction house Sotheby's in Manhattan with a purported Hirst painting in December 2012.
When Sotheby's tried to authenticate the "spin" painting, Hirst's London studio, Science Ltd, said it was a fake.
Sutherland then offered five supposedly Hirst art works to the undercover officer, insisting they were authentic.
More From This Section
He offered two "spin" paintings and three "dot" limited edition prints, called "Valium," "Opium," and "LSD" for USD 185,000.
He was arrested on February 7 last year when he met the detective, assured him of their authenticity and accepted a cash payment.
Hirst's studio confirmed all five pieces were forgeries, the district attorney's office in Manhattan said.
Sutherland, a pastor at the non-denominational Mosaic Miami church, testified that he had previously sold 10 to 12 art works.
"It is particularly important to hold accountable those who fraudulently deal artwork and to preserve the integrity of this market," he said, thanking the jury.
Sutherland's lawyer Sam Talkin told AFP: "We're going to look into all possible appeal issues."
Hirst, 48, is perhaps the most famous of the Young British Artists who dominated the art scene in the 1990s. He won the prestigious Turner Prize for contemporary art in 1995.
Known for his formaldehyde preservations of dead animals and his multi-colored "spot paintings," he is one of the richest artists in the world.