28% of 10-16 year old said they were cyberbullied during the first lockdown earlier this year.
The figure has emerged from the director of the National Anti-Bullying Centre on the first International Day Against Violence and Bullying in Schools.
Director of the group Professor James O'Higgins-Norman says it is a high figure and "extremely worrying".
Last year, UNESCO declared that on the first Thursday of November all countries should highlight bullying - with an overall aim to eventually eliminate it from schools.
Research shows one in three students have been bullied in the past month.
The President has described the findings as "appalling".
President Michael D. Higgins says they are of "deep concern" and demonstrate the need for heightened awareness.
He is calling for bullying and violence to be brought to an end with support from all of us.
