The figure covers the period from January 1 to 20 and shows a 36.8% decrease compared to the same period in 2017.
Meanwhile, disbursements rose by 10.5% to more than US$1 billion.
According to the national statistics agency, the manufacturing sector was the largest recipient of foreign direct investment (FDI), accounting for US$330.6 million, or 74.7% of total pledges.
Ho Chi Minh City led the nation in attracting FDI, receiving US$86.2 million, followed by Nam Dinh and Ninh Thuan province with US$80 million and US$60 million respectively.
Singapore was the largest foreign investor in January, pledging US$147.7 million. The Republic of Korea and Norway were the second and third largest with commitments of US$70.4 million and US$70 million respectively.