Mr Cohen has been with Channel 4 for seven years

He was appointed head of E4 and Channel 4 factual entertainment in 2006, and has commissioned programmes including Skins and Supernanny.

He is replacing Julian Bellamy, who is returning to Channel 4 after being at BBC Three since 2005.

Mr Cohen said the post was a "hugely exciting new challenge" and he looked forward to creating new programmes.

He added: "I believe BBC Three will play a central role in the debate about what public value means for young audiences as we create a whole new generation of programmes across all genres."

Jana Bennett, director of BBC Vision - which controls the corporation's TV channels - said: "He's someone who absolutely understands what young adults are looking for and will bring his flair for innovation to his commissions across all genres."

Mr Cohen is expected to take up his post in the near future. BBC Vision executive Emma Swain will be acting BBC Three controller in the interim.