Online bullying among young people and children as young has seven has increased 88% in five years, the NSPCC has said.
Figures show Childline, the charity's helpline service, counselled 4,541 children in 2015/16, compared to 2,410 in 2011/12.
The levels of bullying - posted on social media profiles, blogs and online pictures - ranged from abusive words about appearance to death threats.
NSPCC chief executive Peter Wanless said: "Online bullying is one of the biggest child protection challenges of this generation. It is a problem intensified by the ever-increasing presence of the internet."
Almost half of young people aged 16-24 who had been bullied said listening to music made them feel stronger.
According to a new YouGov survey, more than half of Britons have been bullied in their lifetime.
The NSPCC have two helplines.
Help for children and young adults, call Childline on 0800 1111. Adults concerned about a child, call 0800 800 5000.
If you are in distress or need some support, the Samaritans are available 24 hours a day on 08457 90 90 90 or visit their website.