The actress - who moved to Ireland earlier this year with youngest child, 12-year-old Clay - is concerned about the state of her home country under the administration of the former Apprentice star and warned "fascism" is on its way.
She told Australia's Daily Telegraph newspaper: "What's coming is fascism in the United States, pure and simple.
"Christian white nationalism, and that's not democracy, and that's not a democratic republic, and you know, that's not who we are.
"We have got to remember that who we are is much bigger than just a Democrat, a conservative or a Republican, or a liberal.
"We are all humans that have the same blood and the same heartbeats and the same needs and the same emotions and the same desire for freedom.
"I feel that if we let them continue on, we are doomed as a democracy."
The 63-year-old comic has applied for Irish citizenship and will be relieved when the process is complete.
She said: "It is self-imposed (political exile).
"I am applying and about to be approved for my Irish citizenship as my grandparents were from there and that's all you need. It will be good to have my Irish citizenship, especially since Trump keeps threatening to take away mine."
In July, the president branded O'Donnell a "threat to humanity" and threatened to revoke her US citizenship after she criticised his administration's handling of the catastrophic floods in Texas that left over 120 people dead.
Trump posted on his Truth Social platform: "Because of the fact that Rosie O'Donnell is not in the best interests of our Great Country, I am giving serious consideration to taking away her Citizenship. She is a Threat to Humanity, and should remain in the wonderful Country of Ireland, if they want her."
Rosie described the Commander-in-Chief as a "dangerous old soulless man with dementia" in a social media riposte to his threat, which is constitutionally impossible.
The talk show host wrote on Instagram: "The president of the USA has always hated the fact that I see him for who he is - a criminal con man sexual-abusing liar out to harm our nation to serve himself.
"This is why I moved to Ireland - he is a dangerous old soulless man with dementia who lacks empathy, compassion, and basic humanity."
O'Donnell continued: "I stand in direct opposition (to) all he represents - so do millions of others - u gonna deport all who stand against ur evil tendencies - ur a bad joke who can't form a coherent sentence (sic)."
O'Donnell is in Australia with her Common Knowledge stage show.
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