UKIP members have voted to sack leader Henry Bolton after controversy over racist messages sent by his partner.
The former army officer's fate was decided after 63% voted to back a no confidence motion at an extraordinary general meeting (EGM) in Birmingham.
He had faced calls to quit after it emerged his partner Jo Marney sent racist messages about Meghan Markle.
Gerard Batten will take over as interim leader and there will be a leadership election within 90 days.
- UKIP delayed MPs libel case settlement
- Bolton defends Jo Marney relationship
- UKIP leader splits with partner after texts
- Profile: Henry Bolton
Following the vote, Mr Bolton, who had been in the job for less than five months, said he feared the result would see UKIP "taken off the battlefield" of British politics for months.
He said: "I think it's going to be difficult to unite the party, what we have effectively had is a rejection of a new draft constitution, a reorganisation and indeed a new way of doing politics."
Mr Bolton again said he had "strong affections" for his former girlfriend, who he said sent him a good luck text message before the meeting.
Asked if he was going to get back together with Ms Marney, he said: "I have said all along that once we got the EGM out of the way I would spend time sorting out my private life."
He was elected in September in the wake of UKIP's disastrous performance in last year's general election.
The party's national executive committee expressed no confidence in him last month, triggering the ballot.
He lost the no confidence motion by 867 votes to 500.
Outgoing chairman Paul Oakden said: "Henry Bolton has been removed by the democratic decision of the membership."
Mr Bolton was the party's fourth leader in 18 months.
He had replaced Paul Nuttall, who quit after the general election - which saw UKIP's vote share shrink to 1.8% from 12.6% in 2015.
Analysis: Alex Forsyth, political correspondent
When Henry Bolton was elected just five months ago, many in UKIP had hoped he'd be the unifying force the party needed, bringing its focus back to Brexit.
But like his two predecessors, his tenure was short lived, and now UKIP is once again seeking leadership and direction.
The party's most senior figures are optimistic that they can find a strong leader who will rally the members and give UKIP a voice in the Brexit debate.
But among some activists who attended the emergency meeting there was frustration, even anger, at the continued turmoil at the top.
Some fear another divisive contest - not least because of the financial implications for the cash-strapped party.
UKIP might survive - most think it will - but for now some don't see how it can regain its place on the political playing field as the influential force it once was.
Mr Batten, London MEP, said UKIP's membership had made the right decision to sack Mr Bolton.
The interim leader said: "I believe that you have made the best decision that you could in the circumstances."
Mr Bolton said he was considering legal action as a result of the way the process to get rid of him was handled, but Mr Batten responded by saying: "Get on with the rest of your life."
Prior to the vote ex-leader Nigel Farage had backed Mr Bolton, saying "for all his faults", removing him would hasten UKIP's path to "irrelevance".
UKIP's leadership changes
- Nigel Farage: UKIP's long-serving leader announced his resignation on 4 July 2016, saying his "political ambition has been achieved" by the Brexit vote
- Diane James: Lasted less than three weeks after being elected in September 2016
- Nigel Farage: Returned as interim leader in October 2016
- Paul Nuttall: Elected on 28 November 2016, but quit the following June after UKIP's general election collapse
- Henry Bolton: Elected on 29 September. Received a vote of no confidence on 17 Februarys path to "irrelevance".