The Act designates a US Postal Service facility in Charlottesville, Virginia, the Captain Humayun Khan Post Office. There follows an extensive controversy from the summer before Trump's victory.
The bill signed by Trump on Friday and more than two years away from the controversy was introduced by Retired Rep. Tom Garrett of Virginia Republican. Both chambers of the congress insisted unanimously.
Sens. Mark Warner and Tim Kaine, both Democrats from Virginia, welcomed the law in a joint statement.
"By dedicating this post office, we show the Khan family that we are forever grateful for his service and sacrifice to our country," it says in its statement.