The ivory was found by customs at the north port of Haiphong in a container that was supposedly carrying peanuts, according to the official logbook.
Photos released by the customs department showed hundreds of long ivory tusks stacked in front of an open container.
The shipment was shipped to Vietnam via Singapore, officials said.
Elephant tusks and other body parts are used as talismans and used in traditional medicine in some parts of Asia, although there is no scientific evidence of such medicinal properties.
Vietnam officially banned the ivory trade in 1992, but the country remains a hub for illegal wildlife transport in Asia.
More than 60 tonnes of ivory, pangolin scales and rhino horn have been seized in Vietnamese seaports since 2018, according to a 2021 report by Education for Nature Vietnam, a non-governmental wildlife protection organization.