Other destinations were Da Nang, Nha Trang, Ho Chi Minh City and Hanoi, based on Agoda's booking data from the first half of this year.
Phu Quoc is loved by return travelers for long, sandy beaches, laid-back charm, and high-end resorts, Agoda said.
The island city received 5.2 million visitors in the first seven months of this year, a 31.8% increase compared to the same period last year.
It also received nearly 980,000 foreign arrivals during the period, up 74%.
From May to July 2025, traditionally the low season for international tourists, Phu Quoc still attracted over 350,000 foreign visitors, marking an average monthly increase of nearly 80% compared to the same period in 2024.
The international tourist market is showing signs of recovery with gains from key markets such as South Korea, China, India, and Europe.
Many foreigners have always returned to visit the island, praising its pristine beaches and modern infrastructure.
The island has received multiple accolades from global travel publications. Recently, it ranked third on Travel + Leisure's list of the 10 best islands in the Asia-Pacific, behind only Bali and Koh Samui.
Last year, it was voted the world's second most beautiful island by Travel + Leisure readers, just after the Maldives.