Over 18,500 visited Vietnam during the month, a 44% increase from the previous month.
New Zealand topped the list of favorite destinations with 96,500 visiting the island nation, followed by Indonesia, the U.K., the U.S., Fiji, India, Singapore, Thailand, and Italy.
ABS statistics showed that Australians spend 19 days in a foreign trip on average.
The Vietnamese government has allowed quarantine-free entry for foreign visitors since March.
It also offers 30-day e-visas for citizens from 80 countries and territories, including Australia.
So far this year the country has received 1.44 million foreign tourists and has a full-year target of five million.