There are hopes a new bridge over a river in the Mekong Delta will help lift Vietnamese people out of poverty.
Australia contributed $160 million in aid money towards the project, which then prime minister Julia Gillard announced in 2010.
Foreign Minister Julie Bishop will travel to Vietnam this weekend to open the Cao Lanh Bridge, in Dong Thap Province alongside Vietnamese Prime Minister Nguyen Xuan Phuc.
"The Cao Lanh Bridge is a visible symbol of the depth of the Australia-Vietnam relationship," she said.
The bridge is the largest single Australian aid effort in mainland Southeast Asia.
An estimated 170,000 people are expected to use the bridge daily.
She said project will help connect 18 million people with regional markets and drive economic growth.
The Asian Development Bank and Korean government also contributed to the project.
Ms Bishop is also expected to have bilateral meetings with her Vietnamese counterpart Pham Binh Minh.
