Pentagon officials said Spc. Vincent Sebastian Ibarria, 21, from San Antonio, Texas had died on Friday in a vehicle rollover in Farah near the Iranian border.
Additional details about the death were not immediately provided as the incident was said to be still under investigation.
The US soldier was the ninth serviceman to die in Afghanistan this year.
As many as 2,450 US servicemen have so far been killed since the US and its allies began invading Afghanistan in 2001, according to the latest figures provided by icasualties.org, a website that tracks fatalities and other data in Afghanistan and Iraq.