Emily Parr has been removed from the Big Brother house for using a racially offensive word to another housemate.
The 19-year-old from Bristol was taken out of the compound at 0330 BST and was forbidden from having any further contact with the 11 other contestants.
A spokeswoman for Channel 4 said that the decision had been taken because "such behaviour won't be tolerated".
This week's eviction vote, in which Emily was nominated along with Shabnam Paryani, has been suspended.
Channel 4 has offered to refund viewers who have already called telephone lines to evict both Emily and Shabnam.
Charley Uchea is the cousin of footballer Kieran Richardson
It stressed the offensive term was not broadcast in the programme during a live stream, and was immediately reported to senior production staff.
The incident will be aired as part of Thursday night's Big Brother highlights show on Channel 4.
The word will be aired the first time it is used, to give the context of the conversation, but will be cut thereafter.
Emily said: "Are you pushing it out, you nigger?" to Charley Uchea, while they were dancing in the living room on Wednesday evening.
Indian-born Nicky Maxwell, who was also present, said to Emily: "Erm, I can't believe you just said that."
Charley said "You are in trouble", adding she was "in shock".
Emily replied: "Don't make a big thing out of it... I was joking."
In consultation with broadcast executives, the decision was taken to remove Emily from the house because she had breached rules governing contestant behaviour.
This includes causing serious offence based on the grounds of race.
Angela Jain, head of the Big Brother commissioning team, said: "The word nigger is clearly racially offensive and there was no justification for its use."
She added: "She [Emily] understands why her involvement has come to an end and she very much regrets what she said.
"I think people watching the show tonight will agree that Emily spoke carelessly rather than maliciously - certainly Charley and Nicky, the two housemates most directly involved in the conversation with her, seemed to accept that she did."
Ms Jain said that the decision had been taken in the wake of the alleged racist bullying of Bollywood star Shilpa Shetty on Celebrity Big Brother earlier this year.
Shetty, at the International Indian Film Academy awards in Sheffield, said: "Intolerance of any form has to be debunked. For a change [Channel 4] has done some good."
The broadcaster was censured by media watchdog Ofcom and ordered to make a series of on-air apologies for the incident, which prompted more than 40,000 complaints.
The housemates learned the news from a statement left by Big Brother
Labour MP Keith Vaz said: "After the Ofcom decision I thought Channel 4 had learnt all the lessons it was possible to learn.
"But I'm afraid they haven't and there's more to be looked at in this whole sorry episode," he added.
A spokesman for the Commission For Racial Equality said: "Whichever way you look at it, the 'n' word is clearly offensive.
The organisation backed the decision to screen the word, saying "people will be able to see with their own eyes that this is a problem that affects real people".
But a spokesman for broadcasting pressure group Mediawatch said: "They shouldn't broadcast any material which is racially offensive," adding that it would undermine the show.