The reward was offered in October 2011 but remains "active" as Washington is seeking information that can lead to al-Baghdadi's location and arrest, Xinhua quoted the State Department as stating in response to an enquiry by the press.
Militants from the Islamic State of Iraq and the Levant (ISIL), which is led by al-Baghdadi, have overrun swathes of territories in northern and western Iraq since early June.
The ISIL declared June 29 the establishment of a caliphate in areas under its control in Syria and Iraq with al-Baghdadi as its caliph, and changed its name into the Islamic State.
In his first public appearance in a video clip posted online Saturday, al-Baghdadi appealed for aid and advice.
"I became your leader, though I am not the best of you, so if you see me right, assist me," al-Baghdadi said in the video. "If you see me wrong, advise me and put me on the right path, and obey me as long as I obey God with you."
The State Department said al-Baghdadi, also known as Abu Du'a, was born in Samarra, Iraq in 1971.