The highway, to cost VND22 trillion ($941 million), will allow direct travel from Hanoi to Moc Chau in northern Son La Province.
Construction by a public-private partnership (PPP) is set to begin this year and finish by 2024.
The investors will bring in VND17 trillion ($727 million) and collect toll for 26 years.
The government will contribute the remaining VND5 trillion ($214 million) in the form of land in the two provinces.
The 85-kilometer expressway will have four lanes and two emergency lanes will be added later.
It will link up with the Hoa Lac – Hoa Binh expressway connecting the capital with Hoa Binh, which opened to traffic last October, halving travelling time to one hour.