Childline has answered almost 600 online contacts, calls and texts from children and young people since December 23rd.
The ISPCC said family relationships, mental or emotional health, and sex, relationships and puberty were among challenges faced by children this Christmas.
Over 70 volunteers gave their time across the festive period to help ensure no child faced their challenges alone.
ISPCC Chief Executive John Church said the majority of calls centred around arguments and family conflicts.
"It's been another very busy year for Childline," he said.
"We know while Christmas is often a magical time for children, it's not so for many, many children.
"The big issue this year was really family relationships, and that really centred around arguments/family conflicts, and that would have got worse as the day went on.
"They've told us about the impact of alcohol and substance abuse in the home.
"They also told us how alone and anxious they felt, and missing loved ones as well".
Post-COVID anxiety
Mr Church said issues around family relationships are "impacting on their mental health and emotional health."
"We've seen this anxiety continue during COVID, and then post-COVID anxiety amongst children and young people.
"That has certainly continued throughout the year".
He said many children saw others celebrating differently.
"Their feelings were exacerbated as they saw families and friends celebrating together and it's not like that for them," he said.
"They turned to Childline for a listening ear and a supportive voice to hear them."
'Incredible dedication'
He also thanked all those who give their time to the charity.
"Our amazing Childline volunteers were there for them 24/7 over December 23rd, Christmas Eve and Christmas Day - as they are throughout the Christmas period.
"We are so thankful for the incredible dedication of our Childline volunteers.
"They leave their own families at Christmas to ensure that there is always someone to listen when a child or young person needs them."
Mr Church said children do not have to be in crisis to call Childline.
"Children can contact Childline for any reason whatsoever - it's not a crisis Childline, it's there for every single reason.
"We're open 24 hours a day, seven days a week, there's always somebody at the end of the line just to even talk about whatever issue how small they feel it is," he added.
Anyone affected by issues raised in this article can contact Childline on 1800-66-66-66 or childline.ie In an emergency, call 999 or 112
