A U.S. congressional delegation was expected to arrive in Tripoli Sunday, another first since the countries severed relations 20 years ago.
Lantos told reporters in Tripoli he was happy to visit Libya, adding Washington was "looking forward to working" with Libya.
He said he would present a report on his talks with Libyan officials when he returns to the United States.
The congressman was greeted at the airport by Libyan legislator Abdul Latif al-Dali and the head of the Libyan-American Friendship Society, Adel al-Daemi.
Al-Daemi said he hoped the congressional visit would be "a real start to restoring strong Libyan-American ties," adding Lantos' presence "confirms that Libya is a safe territory and that we welcome the resuming relations between our two countries."
U.S.-Libyan tension eased last month when Moammar Gadhafi renounced his weapons of mass destruction programs and opened the country's facilities to international inspections.