However, the charity said the increase could indicate that more children were willing to ask for help rather than that victimisation had soared.
The number of children counselled by ChildLine about bullying increased by 42 per cent in the last year, the largest annual rise in the organisation's 18-year history. More than 31,000 children complained of the problem, 8,500 of whom were aged under 11.
Around half reported that they had suffered name-calling and other verbal abuse while a third said they had been punched, kicked or physically assaulted in other ways.
ChildLine said it found it disturbing that a quarter of the children had needed to call the helpline even though they had already raised the problem with their teachers.
But the charity said the growth in bullying reports did not necessarily indicate a rise in the problem in schools.
A ChildLine spokeswoman said: "It's very difficult to say whether there really is more bullying or if the message is getting out to children that they should speak out. We hope it is the latter."
Law firms report that the number of parents taking legal action against schools and education authorities over bullying has decreased in recent years.
Mark Blois of solicitors Browne Jacobson said the decline seemed surprising because of the high profile given to bullying and concerns about compensation claims against schools.
The Department for Education and Skills has been urging all headteachers to sign an anti-bullying charter and last month launched a pound;500,000 Anti-Bullying Alliance to co-ordinate visits by experts to schools.
ChildLine revealed the helpline figures as it launched the ChildLine Foundation, an initiative aimed at raising funds for the charity's work.
www.childline.org.uk; telephone 0800 1111