Natasha Gray, who was voted the UK's sexiest teacher on a television show in 2002, was shown in one photograph wearing a thong while lying on her front on a bed.
Ben Slade, headteacher of Manor Community College in Cambridge, said the pictures of the head of physical education
should not have been published.
"They were completely inappropriate for somebody who is a teacher," he said.
"They were absolutely not pornographic but do you want to see your teacher in that way? Probably not."
Mr Slade said he had ordered the immediate removal of the portfolio of "about eight" photographs from the website iModel.com after he became aware of them.
He said they featured Miss Gray, who is in her early 30s, in a range of poses, including one "lying on a bed on her front in a thong".
"I'm not the sort of person who will accept totally inappropriate behaviour by a member of staff," said Mr Slade.
"I'm in consultation with our personnel department and with the local authority in relation to further action."
He said Miss Gray had not been suspended but added he felt "let down" by her actions.
"We're trying to improve things here. Results have gone up considerably in the last two years - from 32% achieving 5 A-C grades at GCSE to 50%," Mr Slade said.
"I'm extremely disappointed that this member of staff has let us down