Pieta House has launched a "sunrise appeal" to take place on Saturday.
Its annual flagship fundraiser, Darkness Into Light, had been scheduled for that day before being postponed.
Like many charities, Pieta House's fundraising efforts have been hit hard by Covid-19 restrictions.
The mental health charity has had to cut staff's pay and offer redundancies, even though it is noting an increase in demand for the service.
In the place of Darkness Into Light this year, it is asking people to show their support and solidarity with those who have been impacted by suicide and self-harm by watching the sunrise at 5.30am on Saturday and sharing pictures of it with messages of hope for service users and their staff.
"We're noticing an increase in the number of people calling our 24-hour counselling service and we want to continue answering every call and text," Leigh Kenny, Pieta House clinical regional manager, said.
"80% of our funding comes from donations every year and without funds raised from Darkness Into Light, all of Pieta's frontline services are now facing an immediate and devastating financial crisis."
If you have been affected by any issues raised in this story, visit our helpline page.