Anti-gay preacher is the first person ever to be banned from Ireland under exclusion powers
He had praised the gunman who killed 49 people in an attack on a gay club in Florida in 2016.
Steven L Anderson, a Baptist pastor based in Arizona, is already well-known worldwide for telling his congregation in 2009 that he actively prayed for the death of then-President Barack Obama.
He also denied that the Holocaust ever happened, and claimed that homosexuality was something that God punished with the death penalty.
The preacher, with strong anti-LGBTQ and anti-Semetic views, was reportedly set to preach to a congregation in Dublin on Sunday 26 May, but as of yet there had been no set time or location.
However, as reported by The Irish Times, Minister for Justice Charlie Flanagan signed the exclusion act, which effectively bans Anderson from entering Ireland at all.
This is the first time that anyone has been banned from Ireland under the exclusion powers since they were first introduced in the Immigration Act of 1999.
Section 4 of that Act allows the Minister to sign an exclusion order if he or she "considers it necessary in the interest of national security or public policy".
Anderson has already been banned from most countries in the EU, as well as being the subject of an exclusion order for the UK.
Minister Flanagan stated that "I have signed the exclusion order under my executive powers in the interests of public policy."