Housemates Jade Goody, Danielle Lloyd and Jo O'Meara were accused of bullying and making racist comments toward and about Bollywood actress Shilpa Shetty, the show's eventual winner.
Channel 4, which broadcasts "Celebrity Big Brother," said in a statement that it was in talks with other companies to find a new sponsor.
"After three years the Carphone Warehouse has confirmed that it will no longer be sponsoring Big Brother," it said.
Carphone Warehouse and Channel 4 said they would continue to work together on other shows.
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