Extern, which works with people facing homelessness, has been targeted in a ransomware attack.
The charity discovered that its data had been stolen and put on the dark web on Friday 12 April.
Extern works with vulnerable people who are experiencing homelessness or at risk of it.
It also supports children, young people and families dealing with mental health issues, the impact of suicide, addiction problems, refugees, and people that have offended in the past.
The charity said it immediately reported the data breach to the Police Service of Northern Ireland (PSNI) and An Garda Síochána, and began investigating the breach.
Extern said that by 17 April, law enforcement at the PSNI cyber security unit was able to remove its data from the dark web.
In a statement, the charity said: “All relevant regulators and authorities, funding partners and commissioners were immediately notified and kept abreast of the incident.”
An Information Commissioner’s Office spokesperson said: “Extern Group reported an incident to us and we are making enquiries.”
The Charity Commission for Northern Ireland told Civil Society it is aware of Extern’s situation and “will look to ensure the charity trustees manage it properly”.
