The decline has slowed down compared the decrease of 11 percent in the first seven months.
Of this, 1,135 newly-registered projects accounted for $11.33 billion, down 37 percent in volume, but up 16.3 percent in value.
The investment is led by the manufacturing and processing with nearly $9.3 billion, followed by electricity production and distribution with $5.5 billion. Real estate was a distant third with $1.6 billion while the wholesale and retail sector attracted over $734 million.
Singapore was the biggest foreign investor, with $6.2 billion of FDI pledges in Vietnam, followed by Japan, and South Korea.
The Mekong Delta province of Long An attracted $3.6 billion, while commercial hub HCMC accounted for $2.2 billion and Binh Duong got $1.7 billion.
Disbursed FDI in the first eight months was estimated at $11.58 billion, up 2 percent year-on-year.
Last year had seen a 25 percent year-on-year fall in FDI investment to $28.5 billion as the Covid-19 pandemic prevented air travel and dampened investor sentiment.