The soldier "was killed April 29 while conducting operations in southern Iraq," a US military statement released on Saturday said, without giving further details.
The death brought to 11 the number of US troops to have died in Iraq in April, according to an AFP tally based on data compiled by independent website www.icasualties.org.
That is the highest monthly toll since November 2009, when 11 soldiers also died, starkly highlighting the risks American soldiers still face even after combat operations were officially declared over last summer.
Of the 11 to have died in April, six died in what were described as "non-hostile" incidents.
Two were killed as a result of a roadside bomb in Numaniyah, Wasit province, while two others died in separate mortar attacks in Baghdad and Babil provinces.
Around 45,000 US soldiers still remain stationed in Iraq, and while they are primarily charged with training and equipping their local counterparts, they can return fire in self-defence and still take part in joint counter-terror operations with Iraqi forces.
Friday's death also brings to 4,452 the number of American troops to have died in Iraq since the 2003 US-led invasion that ousted Saddam Hussein, according to the AFP tally.