The report found that 68.6% of passenger reviews mentioning staff at Jeju were friendly and helpful, placing it ahead of Jewel Changi Airport at 17th with 65.7%.
Taiwan's Taoyuan International Airport is ranked the world's friendliest.
Cornwall Airport Newquay of England followed in second place, followed by Narita International Airport in Japan.
To compile the list, Airport Parking & Hotels analyzed more than 71,000 Google reviews posted from May 20 to late August that mentioned airport staff at the world's 100 busiest airports and 23 of the U.K.'s busiest.
Within these reviews, it specifically searched for words relaying positive experiences such as "friendly", "polite", "helpful" and "professional" in order to rank the friendliest overall.
Located on the tourist island of Jeju, Jeju International Airport is the second largest in South Korea, just behind Incheon International Airport in Incheon, which was not included in the ranking.