The premier gateway to the country slipped from 54th place last year.
The highest ranking KLIA achieved was in 2001, when it took the second spot on the list.
It has since dropped out from the top 10 since 2013, when it fell to 14th place.
KLIA's previous rankings over the years were 20 (2014), 19 (2015), 24 (2016), 34 (2017) and 44 (2018).
Meanwhile, KLIA2 managed to stay in the top 10 in the World’s Best Low-Cost Airline Terminals list, coming in at number six. Its latest ranking, however, marks a fall from third place last year.
The awards is voted for by customers in a global airport customer satisfaction survey.
"A central directive of the survey is for customers to make their own personal choices as to which airport they consider to be the best, underlining the brand as the passenger’s choice awards, ” Skytrax said in a statement posted online.
Skytrax is an airline and airport consultancy based in Britain.
Its annual World Airport Awards is often regarded as a quality benchmark for the world airport industry, assessing customer service and facilities.
This year, Singapore’s Changi Airport took the top spot for the eighth consecutive year.
In other developments, Malaysia Airports said airports here are well prepared to handle the Covid-19 pandemic as domestic air travel resumes.
"Passengers can be assured that our airports have been disinfected and sanitisation activities have been consistently carried out since the onset of the Covid-19 outbreak, ” it said in a statement.
Malaysia Airports has also stepped up its standard operating procedures by implementing additional precautionary measures to ensure the safety of passengers.
Among the new measures include making the use of face mask compulsory when entering the terminal building.
All non-passenger visitors and greeters are also not allowed into the terminal.