Mr Farron took to his Twitter account to denounce the party after its only MP announced he is to stand down from the party.
In a scathing tweet Mr Farron said: "Douglas Carswell quitting shows UKIP now has no purpose.
"Theresa May is effectively their leader and has adopted their hard Brexit agenda."
Tim Farron says Ukip's days are numbered in a tweet
He was elected twice on a UKIP ticket, with UKIP resources and the hard work and shoe leather of UKIP activists
Bill Etheridge, UKIP
Douglas Carswell said Britain's vote to leave the EU made it the right time to leave the party, adding that he did so "amicably".
Writing on his website, Mr Carswell said it was a "job done" on Brexit, and he would now focus on constituency issues.
He said: "Like many of you, I switched to UKIP because I desperately wanted us to leave the EU.
Tim Farron says that Ukip is facing wipe out
"Now we can be certain that that is going to happen, I have decided that I will be leaving UKIP.
"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.
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"I will simply be the Member of Parliament for Clacton, sitting as an independent.
"I will leave UKIP amicably, cheerfully and in the knowledge that we won."
Douglas Carswell was backed by Nigel Farage but now he's quit
Although the loss of its only representative in Parliament will be seen as a blow by some, there are many within UKIP who will be glad to see the back of him.
Since defecting from the Conservatives to UKIP in 2014 Mr Carswell's relationship with senior party figures, including former leader Nigel Farage and millionaire donor Aaron Banks, has turned irretrievably sour.
Mr Carswell repeatedly called for Mr Farage to step down as leader during his tenure, with the latter calling the MP "irrelevant".
Ukip is facing a new crisis after Carswell resigned
Both Mr Farage and Mr Banks have accused Mr Carswell of trying to destroy the party from within, to the point Mr Banks has even suggested he will stand against Clacton's sitting MP in the next general election.
The bitter public feud reached fever pitch last month when it was suggested Mr Carswell had attempted to thwart Mr Farage being awarded a knighthood.
Mr Farage responded by writing a highly critical piece in the Telegraph, calling for Mr Carswell to quit UKIP.
He wrote: "As a party, how can we let a man represent us in the House of Commons who actively and transparently seeks to damage us?
“I think there is little future for Ukip with him staying inside this party. The time for him to go is now."
Meanwhile Bill Etheridge, who had called for Douglas Carswell to resign, said he was "delighted".
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
He said: "It's a lovely, sunny day and someone I believe was not genuinely interested in representing UKIP in Westminster but has been the focus of serious infighting in the party has gone.
"But I think he needs to step down and call a by election: he might think he can get away with not doing so because he is becoming an independent but I no more believe that than I do the moon is made of cheese.
"He was elected twice on a UKIP ticket, with UKIP resources and the hard work and shoe leather of UKIP activists."