A statement from the Saudi-led coalition in Yemen confirmed that the fighter jet was one of the French-made Dassault Mirage 2000-9s participating in the operations.
The UAE operates alongside the Mirage 2000-9s F-16 block 60s in their Operation Restoring Hope missions over Yemen as well as other logistical and transport aircraft.
"The Supreme Command of the Armed Forces announced today that a fighter jet taking part in the Arab coalition led by Saudi Arabia ... in Yemen was missing," a statement on the official WAM news agency said Monday afternoon, without giving further details.
According to the UAE armed forces, clashes last night and earlier this morning took place in Aden between security forces and al-Qaida militants in the southern capital.
A government official told AFP that a coalition jet had carried out an air raid against the home of a local ISIS commander at dawn, killing the target's 18-year-old son, near the plane crash site.
Coalition Apache helicopters were also taking part in the fighting on Monday, security officials said.
"We saw Apache helicopters fire rockets and open machine gun fire at al-Qaida militants" in the al-Mansoura district of Aden, one witness told the news agency.
This is the first known case of a UAE jet from the coalition crashing since the campaign began in March last year.
In December, a Bahraini F-16 crashed in Saudi Arabia due to a "technical error." The pilot was saved and the plane's wreckage was found.
It was the second coalition jet to crash after a Moroccan warplane went down during a mission over Yemen in May. Its pilot was later found dead and his body was returned home.
The coalition said at the time that the crash had been caused by a technical fault or human error, and it denied rebel claims that they downed the plane.