Kristina Dubrovska, who lives in Macroom, revealed her two sons, aged 11 and eight, and her six-year-old daughter, have come across the game.
“Around two weeks ago, they were watching a YouTuber who was doing a review of a nerf gun,” she said.
“Suddenly, that ugly face popped up and the kids were terrified.
“I didn’t know what it was but the children knew, they said ‘oh it’s Momo’,” she added.
“When I asked my boys about it, they were quite informed about the “Momo Challenge”, they said everyone in class knew about it and some were playing it.”
Ms Dubrovska, originally from Russia, said it is not the first time she has come across such a game. “The game was going strong in Russia a few years ago and it was very dangerous.
“Parents definitely need to be looking out for their children spending time online,” she added.
Sharon Martin, whose children attend the same school as Ms Dubrovska’s, revealed that children in the school are talking about the Momo Challenge and encouraging people to play it.
“I was actually contemplating writing a note into the school to inform teachers that kids are talking about this game and encouraging people to play it,” she said.
Ms Martin added that after seeing an image of the Momo character, her six-year-old son had nightmares about it.
She acknowledged claims the challenge is merely a hoax or one of a number of games reportedly targeting children.
However, Gardaí released a warning last week asking parents to be vigilant when it comes to the “disgraceful game”.
“A lot of parents are saying they’ve seen it, that it’s popped up and terrified their children, so how can it be fake?” asked Ms Martin.
“People are saying it’s fake but kids are coming home saying their friends are playing it.
“It’s terrifying, very damaging and very sinister,” she added.
Professor Ella Arensman, Chief Scientist at the National Suicide Research Foundation, called for greater international collaboration to prevent games such as the Momo Challenge harming children.
Speaking to the Echo, Professor Arensman said the game seems “to really have taken off in Ireland and Northern Ireland”.
“Social media goes beyond any jurisdiction so it is very difficult to control,” she added.
“We would be recommending greater international collaboration on establishing safety with regards to social media to prevent harm and self harm caused by these mechanisms.”