Officer Dang Van Hanh said Monday the live snakes were taken to a wildlife rescue center near the capital where they treated before being released into the wild.
King cobras are the world's longest venomous snake, and grow up to 5.5 meters (18) feet.
The meat of the king cobras is considered a delicacy by some in Vietnam, where hunting and trading the snakes is banned. The snakes are also sometimes preserved in traditional medicines.
The snakes, which were kept in green sacks, were seized Friday.
Hanh said the car driver told officers he was paid to transport them. Local media reported he was paid under $50.