His departure was confirmed by CBS, which reported it came after months of conflict between him and Defence Secretary Pete Hegseth.
The youngest-ever army secretary has often been referred to as President Donald Trump's "drone guy".
Driscoll, 41, has been "highly effective" in advancing Trump's so-called agenda "to Make America Strong Again" and provided "outstanding leadership" during military operations, the White House said in a statement given to CBS.
MNA