The carrier told a news conference it hoped to return with an additional order for narrowbody planes and that it was also studying long-haul operations very seriously.
"In the United States, there are 3 million Vietnamese overseas, they are waiting for the long-haul direct flying from U.S. to Vietnam," airline Chief Executive Nguyen Thi Phuong Thao said.
VietJetAir started flying at the end of 2011 and operates a fleet of 25 Airbus A320-family aircraft on a network covering Vietnam and other destinations across Asia.
The carrier has now ordered a total of 69 aircraft from Airbus and also holds purchase rights for another 30 planes, Airbus said.
"This confirms the trend that in countries like Vietnam in southeast Asia there is huge potential, huge demand, where low-cost carriers are bringing value," Airbus Chief Executive Fabrice Bregier said.