One in five undocumented people have lived in the State for more than 10 years, according to new research.
The study for the Migrants Rights Centre Ireland (MRCI) estimates there are between 20,000 and 26,000 undocumented migrants living here at present.
The overwhelming majority (81 per cent) have been in Ireland for five years or more and 21 per cent have been in the country for more than 10 years.
Some 86.5 per cent entered the country legally and subsequently became undocumented.
A similar percentage (87 per cent) are working and more than half have a third-level education.
The five most common nationalities among undocumented people living here are:
Filipino, Chinese, Mauritian, Brazilian and Pakistani.
The research is the first of its kind and involved 540 responses from undocumented migrants.
MRCI spokeswoman Helen Lowry said the survey was the first of its kind and provided an accurate picture of undocumented migrants in the country.
She said it was clear most undocumented migrants were long-term residents in Ireland.
She added: “Given that one third of those surveyed have children living in Ireland, the Government simply cannot continue to ignore this population and hope they will all just leave.
“Undocumented migrants are part of our communities, they have put down roots, made Ireland their home - and for many of these children, Ireland is the only home they have known.”
In a case study published as part of the research one undocumented person living here, referred to as Abdullah, compared the experience of undocumented migrants living in the State with undocumented Irish in the United States.
“This research shows that most undocumented people are like me: young, hard-working, educated and committed to Ireland both financially and emotionally,” he said.
“Last year my father passed away; it was so hard for me not being there. All we’re asking for is a chance to come forward and regularise our situations - to be able to visit our families, to move on with our lives and to stop constantly looking over our shoulders.”
The research will published by John Douglas, president of the Irish Congress of Trade Unions, this morning.