Until 1949, an airstrip at Waterloo served the city of Freetown. Because of subsidence of the runway and the proximity of the hills, the Government decided in 1947 to abandon Waterloo and make Lungi, a British Royal Air Force base, the airport for Freetown. Waterloo airfield was closed in June 1949. The senior architect of the Public Works Department, Robin Halliday Macartney, supplied a draft plan for the terminal building, which then became the responsibility of the airport engineer A. E. Pugh. The plans had to be altered considerably to comply with new medical regulations and work did not start before 1953. The control tower had been built in 1952. The new terminal building, finished in 1955, soon proved to be too small, and in 1960 it was decided to make Lungi a modern international airport. A new terminal building was erected to designs by Nickson & Borys and was officially opened on June 25, 1964. The building was expanded for the 1980 OAU summit.

The airport was operated by the Sierra Leone Airports Authority. In 2012 its management was contracted out to the British security and military company Westminster Aviation Security Services Ltd.

The government of Sierra Leone undertook a general upgrade of the terminal in 2010, in order to meet the basic standards of current international airports. The departure hall was commissioned in February 2013 and the arrival hall in May 2014.

From September 2014, almost all regional and intercontinental flights to Freetown were suspended as a result of the 2014 West Africa Ebola virus outbreak. During this crisis, Brussels Airlines was the only carrier to maintain its regular operations to the airport; catering almost exclusively to NGO health workers. The first airline to resume commercial flights after suspending them was Air Cote d'Ivoire in October 2014 while Air France announced it would resume services by June 2015. British Airways chose not to resume flights to Sierra Leone. A national airline Fly Salone operated briefly at the start of 2016. This was the first national airline to operate for more than 10 years after Sierra National Airlines stopped flying. After last having served Freetown in December 1996, KLM restarted flights in March 2017, but discontinued them in 2019. ASKY Airlines recommenced flights in November 2017.

A new international airport was planned at Mamamah to replace Lungi International Airport. Mamamah International Airport was expected to be operational by 2022. The project was cancelled in October 2018 following a change of government. The government Aviation Minister stated that they would refurbish Lungi instead and may build a bridge to better link the airport to Freetown. The Lungi Bridge project was announced by president Julius Maada Bio in 2019.

Following parliamentary approval in December 2020, a $270 million expansion project started. The project included a new passenger terminal, VIP terminal, taxiways and widening of the runway. The annual capacity was planned to be 1 million passengers and would be capable of handling 8 wide-body aircraft at any one time. The new terminal is located on the northern side of the runway, towards the eastern end. The new terminal was officially opened on 4 March 2023. A management agreement was signed with Summa Airport (SL) Ltd.