The man was on temporary release for a work placement when he fled on Monday.
Prison officers raised the alarm at 5pm on Monday.
Advertisement
Contacted for comment, the IPS said it had informed gardaí of the situation.
The IPS said: "The Irish Prison Service can confirm on October 26, 2020, a prisoner on Temporary Release to work placement at Mountjoy Prison went unlawfully at large.
"An Garda Síochána has been notified."
