At the end of his sentence, Michael Hegarty will be on supervised release for three years, the Department of Justice said in a statement.
He was convicted in Florida of buying a “libation cup” of carved rhinoceros horn from a North Carolina auction house and then falsifying documents to smuggle it out of the United States.
Prices for ornate rhinoceros horn cups have exploded on Asian art markets in recent years.
Hegarty was the subject of an Interpol Red Notice requested by US authorities. He was arrested last January in Belgium and then extradited to the United States to face the charges from 2014.
Investigators linked him to the Rathkeale Rovers, a transnational organized crime syndicate responsible for trafficking rhino products worldwide, the Department of Justice said in the statement late Tuesday.
Another Irish national was sentenced in January 2016, in Texas, to 12 months in prison for his role in the rhino horn trade.
Patrick Sheridan and his accomplices bought a rhinoceros head from a taxidermist, then resold the two severed horns of the African black rhino, a critically endangered sub-species.
US authorities have carried out a years-long crackdown on criminal trafficking in rhino horns, dubbed “Operation Crash.”
Despite such efforts, there is persistent demand for products derived from rhino horn in China and Vietnam, where they are coveted as a traditional medicine and aphrodisiac.
According to the International Union for Conservation of Nature, some rhino sub-species are already extinct.
The Javan rhino is among those critically endangered, with about 60 left in the world.