Fawaz Yunus, who was affiliated with the Amal Militia in Lebanon and jailed in the United States in 1989, was released from a prison in Virginia and deported on Monday.
"Not only is he a terrorist, but he's a convicted felon," US Immigration and Customs Enforcement Director Victor Cerda said on Tuesday.
"The law simply does not allow aliens of such notoriety to remain in the United States," Cerda added.
Yunus and four other armed men hijacked Royal Jordanian Airlines Flight 402 in Beirut in June 1985 and threatened to kill the hostages.
After two failed attempts to fly to Tunis, the hijackers returned the plane to Beirut, where they released the hostages, including two US citizens, and blew up the plane.
The hijackers fled, but Yunus was caught and extradited in 1987 to the United States to stand trial for air piracy, hostage taking and other crimes.
It was the first such case of a person tried in the US for crimes against American citizens abroad. He was convicted two years later in a federal court.