US prosecutors said Joseph Asmar, 43, of Beirut, entered his plea at a hearing before US District Judge Eric Vitaliano.
Asmar had been arrested in Paris in October 2015, and was extradited to the United States 14 months later. He had also faced a money laundering charge.
Aaron Altman, a lawyer for Asmar, said in an email: "ggggJoseph Asmar has taken responsibility for his actions and is anxious to move forward with his life. More than anything, he misses his family and prays that they will be reunited in the near future."
Hezbollah is a Shi’ite Islamist political and military group in Lebanon that the US Department of State designates as a foreign terrorist organization.
Asmar was charged following what prosecutors called a two-year sting operation in which he and a Lebanese businesswoman, Iman Kobeissi, had meetings with an undercover US Drug Enforcement Administration agent posing as a trafficker.
Prosecutors said Asmar claimed to be an attorney who boasted that his connections at European and Middle Eastern banks enabled him to launder money, and that he could use his Hezbollah connections to provide security for drug shipments.
Undercover agents provided $400,000 in alleged drug proceeds to Asmar and his co-conspirators, who laundered the money in exchange for a commission, prosecutors said.
Asmar faces up to 20 years in prison. A sentencing date has not been set. Kobeissi's case is still pending.The case is US v. Asmar, U.S. District Court, Eastern District of New York, No. 15-cr-00491.