More than 800 children contacted Childline between December 23 and Christmas Day — a 12% increase on last year's figures.
According to new data from the Irish Society for the Prevention of Cruelty to Children (ISPCC), 820 kids contacted the 24-hour helpline over the Christmas period.
The ISPCC said volunteers received calls on topics such as suicide, abuse, neglect, bereavement and loneliness from children this Christmas.
It said there was a noticeable trend whereby children who engage with its volunteers are at a serious high-risk of harm.
Speaking about the figures, Childline co-ordinator Elizabeth Donlon Fox said they expected to receive more than 250 calls from children and young people on St Stephen's Day.
She said: "It will be one of the busiest days of the year for our team of staff and volunteers at Childline, and we expect that over 250 children and young people will reach out to us today because of something that has happened to them over Christmas.”
ISPCC chief executive John Church said for too many people, Christmas "simply doesn't happen".
He explained: "They turn to Childline for support, and our amazing staff and volunteers are there for them 24/7 over Christmas, as they are throughout the year."
The ISPCC said 50 children a year are in the process of trying to take their own life while on the phone to the Childline team.
More than 200 actively suicidal children have contacted Childline during the last year, while the Childline team has had 1,300 suicide-related contacts over the past 12 months
- If you are affected by any of the issues raised in this article, please click here for a list of support services.