This is higher than in other countries, where one in five 13-to 18-year-olds reported being the target of online harassment, on average.
Almost half of the Irish teens said they felt helpless when it happened to them, with three in 10 admitting to feeling completely alone.
As many as 25pc, one in four, of those who had been cyberbullied went so far as to experience suicidal thoughts as a result.
The figures have emerged in a global survey of almost 5,000 teenagers across 11 countries, including Ireland.
It was conducted by pollsters YouGov on behalf of telecoms company, Vodafone.
Nine in 10 Irish teens said they would find it easier to cope with cyberbullying if they received support from their friends on social media.
However, four in 10 admitted that they would find it hard to find the right words to support a friend who was being bullied online.
The findings were released at the launch of Vodafone’s #BeStrong anti-cyberbullying initiative, which aims to build emotional resilience amongst teens online, and includes the creation of ‘support emojis’.
These can be used to convey compassion, sympathy and support when friends are being bullied online.
The emojis were designed by a panel that included Berkeley University, California, Professor Dacher Keltner, the psychologist who advised on characters for Pixar film ‘Inside Out’.