A total of 16,614 people were living in emergency accommodation in September, according to figures from the Department of Housing.
This represents an increase of 261 from the previous month, when 16,353 people accessed the services.
Some 5,238 children were living in emergency accommodation last month, an increase of 93.
The number of children who are homeless and living in emergency accommodation exceeded 5,000 for the first time in July.
The latest figures showed 2,443 families were living in emergency accommodation.
The vast majority (71%) of adults who accessed emergency accommodation were living in Dublin.
Of the adults in homeless accommodation last month, 60% were men and 40% were women.
Irish nationals made up 50% of adults who accessed the services, the latest figures show.
There were 1,974 people aged between 18 and 24 living in emergency accommodation, while 53% of adults in emergency accommodation were in the 25 to 44 age bracket.
A total of 261 people aged over 65 accessed emergency accommodation in September.
The figures for September this year represent an increase of 12.5% from September 2024, when 14,760 people were living in homeless accommodation.
The number of children in emergency accommodation has increased by 14.8% in the same period.
Children wondering 'where they'll sleep tonight'
Executive Director of the Simon Communities of Ireland Ber Grogan said children should be "thinking about dressing up and going trick or treating, not wondering where they'll sleep tonight".
"In a country that prides itself on progress, the length of time that some of these children have spent in insecure and inappropriate accommodation because of a lack of appropriate move-on options, is disgraceful.
"We urgently need an all of government response to deal with this crisis and save children from the trauma of homelessness," she said.
CEO of Dublin Simon Community Catherine Kenny said the figures are "nothing short of shameful".
"Homelessness remains at record levels heading into another winter. Every number represents a person without the security of a home.
"What’s needed is a comprehensive set of measures that combines efforts across housing, health and social care, specific to those in emergency accommodation.
"This should be outlined in the upcoming housing plan."
Chief Executive at Focus Ireland, Pat Dennigan, said he was "looking forward" to the Government soon publishing its new homeless and housing strategy.
Speaking on RTÉ's Drivetime, he said: "We believe that really has to be a radical change in the way homelessness is addressed.
"Because the plans that have been in place up until now haven't worked."
Mr Dennigan said Focus Ireland has asked the Government to prioritise the charity's five-point plan to end child homelessness.
Mr Dennigan said these steps can achieve the "goal of no child without a home".
Govt concerned about situation, says Taoiseach
Earlier, Taoiseach Micheál Martin said the Government is very concerned about the homelessness situation.
"In the Budget, Minister James Browne has secured funding to focus and prioritise families who are in emergency accommodation, and that will yield results this years in terms of getting families," he said.
Mr Martin also said homelessness is much more complex than it was in the past.
"There is increasing evidence that as people move out of direct provision with family reunification, some are falling into homelessness which is something we have got to review," he said.
"In terms of the nature and composition of homelessness, it’s much different than it would have been five or 10 years ago, but that doesn’t mean we’re not going to do everything we possibly can to deal with it."
He said housing first is key, as well as ringfenced funding to get families out of emergency accommodation as quickly as possible.
Meanwhile, Sinn Féin's housing spokesperson said the Government's new housing plan must prioritise ending homelessness by 2030.
Eoin Ó Broin said the report "shows yet another grim rise in the number of people experiencing homelessness".
Mr Ó Broin said the number of people experiencing homelessness is closer to 22,000 when those in emergency accommodation and rough sleepers are taken into account.
Level of homelessness an 'absolute catastrophe' - Hearne
Social Democrats housing spokesperson Rory Hearne said that the level of homelessness is now an "absolute catastrophe" and a "shameful milestone".
He blamed the increase on evictions from the private sector and said in the first six months of the year there were almost 10,000 notices to quit, meaning that almost 10,000 evictions will happen in the coming months and years.
He called for an emergency outright ban on evictions, especially for families.
On reports of a tightening of entitlements for Ukrainians in State accommodation, he said "the idea that we're running out of accommodation is a completely false narrative".
"It is a false policy reality that the Government are putting out when if they actually built what they should have done, which was State accommodation, they could avoid this."
Labour TD 'sick and tired' of raising homelessness crisis
Labour's Spokesperson for Housing Conor Sheehan has criticised the Government over its "failure" to address the homelessness crisis, saying he is "sick and tired" of raising the issue when new figures are published at the end of every month.
Speaking with reporters at Leinster House, Deputy Sheehan said the situation is unacceptable.
The Labour TD said he is "sick and tired of saying the same thing" every month about the figures while "we are still waiting to see a housing plan or a framework" from the Government.
He said there was "nothing new in the budget" to address the situation, and predicted that if figures continue to rise they could "hit 20,000 by the end of this Dáil" in 2029.
Asked if Minister for Housing James Browne should resign over the ongoing record homelessness figures, Deputy Sheehan said what he wants is for the Minister to "bring forward a housing plan".
He said Minister Browne "has been in office a year" and "can act urgently when he is lowering apartment standards", but "doesn't seem to have the same urgency" when it comes to addressing the homelessness crisis itself.
Additional reporting: Sandra Hurley, Fiachra Ó Cionnaith
