Herve Gourdel, 55, was in the captivity of the Islamist group Jund al-Khilifa since the weekend. He was abducted on Sunday while on holiday in Algeria.
The group released a video entitled Message in Blood for the French government showing the beheading of Gourdel.
The kidnappers had threatened to kill Gourdel in a video on Tuesday unless France ceased its air strikes in Iraq, where ISIS terrorists control vast swaths of territory under the guise of a ‘caliphate’.
“This armed group has asked me to demand that you do not intervene in Iraq. They are holding me hostage. I beg you, Monsieur President, to do all in your power to get me out of here,” Gourdel said in a short message to French President François Hollande.
The air force of France joined the United States last week in carrying out strikes against Isis positions in Iraq.