Donnelly, 24, from Shrewsbury, lost the public vote involving four other housemates.
As he walked out, he was greeted with a mixture of boos and cheers from the crowd waiting outside the house.
Halfwit – real name Freddie Fisher – was saved by the public for the fifth time in a row. He is the favourite with bookmakers to win the Channel 4 series.
Visual merchandiser Donnelly became the fifth official housemate and sixth person to be evicted from the latest series of the reality show.
In addition to Halfwit, he was also up against Marcus Akin, Charlie Drummond and Dogface – real name Sophie Reade.
Channel 4 said he received 63% of the public vote.
Housemates gasped in shock when host Davina McCall announced that Donnelly had been voted out.
When asked by McCall in his post-eviction interview whether Dogface was his girlfriend, Donnelly said: “We haven’t had the chat yet. I do really care about her – honestly.”