The Ukip leader accused the Clacton MP of “always” being a “staunch Tory” and suggested Carswell should grow up after never consulting him on the decision.
In a damning article for the Sunday Telegraph, Mr Nuttall writes: “When he has spoken about the need for more ‘grown-ups’ in politics, I had hoped he would do more to lead by example."
He adds: “Over the last year it has become clear that he has been drifting in one direction while Ukip has been marching in another.
“He has always been and always will be at heart a Brexit supporting staunch Tory, and with the referendum result sorted he has no reason to stay in a party that is moving into Labour’s turf rather than going in a direction that would make him feel more at home.”
Mr Nutall’s comments come amid a bitter civil war in the party after Carswell – Ukip’s only MP – announced in a blog post he was to defect and serve his constituency as an independent.
Nuttall accused Carswell of "always" being "a Tory"
The Ukip leader responded furiously to the announcement after only finding out about it in a text from a friend.
Mr Carswell argued in the post that because Brexit was now “certain” there was no reason to remain in Ukip.
He wrote: “On Wednesday, the Prime Minister is going to trigger Article 50, beginning the formal process of withdrawing our country from the EU.
Arron Banks challenged Carswell to a by election
“By April 2019, Britain will no longer be a member of the EU. After twenty-four years, we have done it. Brexit is in good hands.”
He added: “Like many of you, I switched to Ukip because I desperately wanted us to leave the EU. Now we can be certain that that is going to happen, I have decided that I will be leaving Ukip.
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“I will not be switching parties, nor crossing the floor to the Conservatives, so do not need to call a by election, as I did when switching from the Conservatives to Ukip. I will simply be the Member of Parliament for Clacton, sitting as an independent.”
But the 45-year-old has previously come under fire from Ukip’s biggest donor, who challenged Carswell to stand against him in a by-election.
Arron Banks said the people of Clacton deserve a say on Mr Carswell’s future as their MP, and accused him of acting in self-interest when he defected from the Tories.
Mr Banks said: “Douglas Carswell's departure is a rare piece of good news for Ukip.
The many faces of Nigel Farage Tue, March 14, 2017
UKIP leader Nigel Farage is certainly animated!
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Nigel Farage arrives at BBC Broadcasting House in London
“Carswell has been nothing but a source of division for the party since he joined – a point which Nigel (Farage) and I have stressed constantly for months now.
"His resignation is a good first step, but Ukip will remain in a state of constant dysfunction until the rest of Carswell's Tory cabal follows him out of the door."
Despite Mr Banks’ challenge, it is unclear whether he would be able to stand as a candidate for Ukip after leaving the party and announcing this month he would start a political movement.
Nigel Farage said he was "very, very please" with Carswell's departure
It has been claimed Carswell “jumped before he was pushed” by resigning ahead of a meeting with Ukip’s national executive on Monday over whether he had blocked a knighthood for party veteran Nigel Farage.
Mr Farage said he is “very, very pleased” about Mr Carswell’s resignation, and accused him of “wilfully” undermining Ukip “for the last couple of years”.