Two hundred and fifty homeless families have been left to their own devices, campaigners said.
Focus Ireland said those without state-appointed case managers were four times less likely to move out of homelessness.
The charity told an Oireachtas committee the homeless should not have to be responsible for finding emergency accommodation for themselves in a crisis situation.
Advocacy director Mike Allen said: "A family that has a case manager is four times more likely to move out of homelessness than a family that's left to their own devices.
"From every point of view to invest in an adequate level of case managers makes sense."
The charity has urged an eradication of self-accommodation, where homeless families have to try to find somewhere to stay themselves and the State pays for it.
Last year Focus Ireland supported over 700 families who were in homeless services into secure housing.
In total, the charity worked with over 14,000 people last year either to prevent them from becoming homeless or provided them with housing.
Details of two evidence-based reports, commissioned by Focus Ireland, were discussed at an Oireachtas committee on housing, planning and local government on Wednesday.
Mr Allen said the self accommodation issue continues to be an enormous problem.
"Once a family has been assessed as homeless under the legislation by the local authority, the local authority believes it fulfils its statutory obligation by saying go and find accommodation and we'll pay for it."
He said 250 families are self-accommodating.
"There is a big difference between being in a commercial hotel, and knowing you're going to be there for six months, and being in a commercial hotel and being out tomorrow night and have to look for another place.
"There are over 250 families who have no case manager."
He added the reports identify key things that could make substantial difference to the experience of families and the likelihood of them getting a home.
The committee heard that the families who were at risk of homelessness fell into two categories: issues with landlords and failure to pay rent were greatest issue.
Sean O'Siochru, co-author of the Keeping a Home report, said: "About 80% had experienced notice to quit or simply couldn't pay where they were living which I think doesn't come as a surprise but does say a lot."
The latest figures showed more than 8,500 people were homeless and in some form of temporary accommodation at the end of December, down from 8,800 the previous month.
In total, 3,079 children and 1,408 families were among those in emergency shelters, family hubs, hostels, B&Bs and hotels.