Andrew Fagan, from Naas, Co Kildare, succeeds Phil Garland, who was director since the service was set up in 2003.
The post was vacant since before the publication of the Murphy Report last November.
Mr Fagan has worked with state child protection services in the Republic and the North. He has also managed residential services for children.
He takes over a staff of eight in the Office for Safeguarding and Child Protection in Dublin.
The office implements child safeguarding practices and offers training and support services to over 2,000 volunteers in the diocese's 199 parishes.
In addition to providing support for abuse victims, it monitors and supports clerics accused of child abuse.
SIC: II