Coulter was to be interviewed by Morgan on Wednesday, but cancelled in order to guest on Sean Hannity's Fox News programme instead. Hannity and Piers Morgan Tonight air opposite one another at 9PM ET.
When Coulter promoted her Hannity guest spot on Twitter, Morgan fired back: "Wow. In that case you just banned yourself for life from my show. Congrats."
Morgan interviewed Coulter in June, but clashed with the Demonic author when she refused to answer any questions about her private life.
Madonna and Heather Mills have also been banned from ever appearing on Piers Morgan Tonight.
Coulter recently garnered controversy after she referred to the late Princess Diana as a "anorexic, bulimic narcissist".
Piers Morgan Tonight is broadcast weeknights at 9pm ET on CNN and at 8pm BST on CNN International.
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Watch a clip from Piers Morgan's June interview with Ann Coulter below: