From 1943 to the end of World War II in 1945, Roberts Field Airport, as it was then known, served as an alternative base for a contingent of 26 Squadron SAAF which flew Vickers Wellington bombers on anti-submarine (U-Boat) and convoy escort patrols over the Atlantic.

In fact, from the end of World War II until 1985, the airport was administered and operated by Pan American under contract with the Republic of Liberia's Ministry of Transport.

Monrovia was consistently a key link in Pan American's African network, usually an intermediate stop between Accra and Dakar, from which service continued onward to Europe and New York.

[12] Similarly, VARIG employed RIA as a stop on its flights between Brazil and Europe, which began in the mid-1960s and lasted at least until the mid-1970s, with various routings including Rio de Janeiro-Monrovia-Rome and Rio-Monrovia-Madrid-Rome.

After the end of the civil war in 2003, commercial air service was slow to return to Liberia, and only gathered momentum after the inauguration of President Ellen Johnson Sirleaf in January 2006.

Royal Air Maroc started flights to Mohamed V International Airport in November 2007,[21] and Virgin Nigeria added Monrovia to its network, from Lagos via Accra twice per week, in October 2008.

[22] Also in October 2008 U.S. carrier Delta Air Lines announced that, as part of a major expansion of its route network in Africa, it would begin a once-weekly service between Atlanta and Monrovia, via Sal, Cape Verde.

However, Cynthia B. Nash, a prominent Atlanta businesswoman, stated in an interview coinciding with her appointment as Liberia's Honorary Consul in August 2009 that she expected Roberts International to upgrade its security to meet TSA standards and for the Delta to launch the flight "within the year.

A decline in global prices for commodities such as gold, iron ore and oil began in 2013 and 2014,[33] causing an immediate slowdown of Liberia's extractive-dependent economy,[34] which in turn pressured the viability of the many new intercontinental services from Robertsfield.

The first major blow to the airport's renaissance came in late June 2014, when Air France scrapped its flight to Liberia, citing lack of profitability.

[35] An even bigger loss to the airport in terms of capacity, connectivity and prestige came when Delta Air Lines announced that, after nearly four years of service, it would cease flights to Monrovia on 31 August 2014 due to weak passenger demand.

[40] Robertsfield's small, single-story terminals, in use since the end of the Civil War, were often overcrowded and did not conform to modern aviation standards, nor meet with the requirements set by the ICAO.

In addition, the poor condition of RIA's single runway had been recognized as inadequate since at least 2012, when an Air France flight from Paris suffered significant damage to its landing gear, brakes and hydraulic systems during an arrival on the patched and potholed asphalt, an incident which cost as much as half a million dollars to the airline's plane and was cited as a contributing factor to the airline's decision to end service to Liberia .

[41] The renovation project launched in 2018 completely overhauled nearly every aspect of the airport to meet international civil aviation regulations and allow for expanded passenger and cargo operations.

New car parking facilities and access roads were added to the landside area, while water supply sewage treatment, electrical and communication systems were also upgraded, adding new fire-fighting equipment and other safety systems, as well as mobile equipment including forklifts, ambulances, conveyor belt loaders, in addition to passenger stairs and buses for remote stand deplaning.

[42] The new 5,000 m2 two-level main passenger facility salvaged the structure of the airport's original terminal, which had been destroyed during the Civil War and sat burnt-out and vacant for nearly 15 years.

In November 2014, the European Investment Bank (EIB) agreed to provide a $27.3m (~$34.6 million in 2023) loan over a period of 20 years to the Liberian government in support the rehabilitation project at the RIA.