Muath believed it was his duty to fight those destroying true spirit of Islam
Lieutenant Muath al-Kasaesbeh (26) fell into the hands of Isil militants in December 2014, when his Jordanian F-16 plane crashed near Raqqa, Syria: the de facto capital of the group's self-styled caliphate.
He was the first pilot from the US-led coalition to be captured.
The pro-Isil Raqqa Media Centre (RMC) posted pictures of the pilot surrounded by more than a dozen militants, some masked, shortly after he was seized.
It also released images of the militants posing with pieces of wreckage.
A friend said Al-Kasaesbeh, who comes from a prominent Jordanian family, was strongly committed to his mission and felt it was his religious duty to fight extremist groups that were "distorting the true spirit of Islam".
He was married to Anwar al-Tarawneh.
Last night the country was both shaken enraged as his brutal death was confirmed a the hands of the extremist group, and "punishment and revenge" was vowed.
"The military forces announce that the hero pilot, Muath al-Kasaesbeh, has fallen as a martyr.
Armed forces spokesman Mamdouh al-Ameri said: "While the military forces mourn the martyr, they emphasise his blood will not be shed in vain.
"Our punishment and revenge will be as huge as the loss of the Jordanians."
The BBC's security correspondent, Frank Gardner, reported that the new and horrific video is aimed at a world already shocked by the calculated cruelty of Isil's actions.
Hundreds were gathered outside the hall on the outskirts of Amman where family members and friends of the Jordanian pilot have been congregating for days.
As the news emerged, people prayed in commemoration for his life and gathered around mobile phones looking at the gruesome images circulating on social media.
Immediate family members have not spoken, but an uncle of the pilot told the BBC that Jordan must act against such extremists. As the evening went on more Jordanians gathered.
Angry shouts went up calling for unity and chanting the pilot's name. But some have also called out against Jordan's participation in the coalition.
Jordan had been attempting to secure Lt Kasaesbeh's release as part of a prisoner swap, offering to free Iraqi militant Sajida al-Rishawi in exchange.
She is a failed suicide bomber now on death row in Jordan for her role in attacks in the capital, Amman, that killed 60 people in 2005.
Isil had sought Rishawi's release as part of a deal to free captive Japanese journalist Kenji Goto.
A video that appeared to show Goto's dead body appeared three days ago.
Last night Jonathan Marcus, the BBC's diplomatic correspondent, commenting on the latest atrocity said: "One thing is clear from this video - Isil never had any intention of releasing the young Jordanian pilot.
"According to Jordanian state media, he was killed on January 3, well before the supposed prisoner exchange talks moved into high gear.
"The cynical manipulation of this episode by Isil shows the importance it affords to information warfare - here an attempt to create problems for the Jordanian authorities and to weaken the Arab-Western coalition, at a time when it appears to be struggling to make dramatic headway against Isil on the ground."
"This is the problem for the coalition. Its air campaign is in many ways a stop-gap intended to halt the progress of Isil, but requiring effective troops on the ground to significantly turn back its advance, " he said last night. (© Independent News Service)
Independent News Service