Virgin Australia plummeted from 13th place in 2017 to 22nd this year, just ahead of Russia's Aeroflot.
Air Canada was named Best Airline in North America, while Air Transat was named Best Leisure Airline in the World.
The last time SIA took home the gold award was in 2008, and a year ago it came in second in the ranking done by London-based research firm Skytrax.
A Singapore Airlines Airbus A350-900 plane takes off at Changi Airport in Singapore March 28, 2018.
It was honored during the Skytrax World-Airline Awards ceremony, held in London, in the presence of flynas' CEO Bander Al-Mohanna and members of the senior management.
In terms of the overall victor, Singapore Airlines overtook Qatar Airways as the world's best airline.
Along with being one of the most respected travel brands in the world, Skytrax editors point out that Singapore Airlines flies one of the youngest aircraft fleets in the industry, with a network that spans six continents. The awards tend to favour the bigger airlines but are seen as a useful guide to how they are delivering customer service.
Other accolades include China Southern Airlines winning the world's most Improved airline, continued success for Garuda Indonesia being named the world's best cabin crew, Norwegian as the best long-haul low-priced airline. Skytrax pay all costs of the Survey and Awards event.
AirAsia, which flies to Auckland from Malaysia, continued dominance being named the world's best low-priced airline. ANA All Nippon Airways, Emirates and EVA Air comprise the rest of the top 5.
Celebrating their 18th anniversary, the World Airline Awards are independent and impartial, introduced in 1999 to provide a customer satisfaction study that was truly global. The survey itself was offered in English, French, Spanish, Chinese, Russian and Japanese. All survey entries were screened to identify IP and user information, with duplicate, suspect or ineligible entries deleted.