Integrated Family Support Services (IFSS) aims to keep families together by helping parents tackle their problems.
Counties in the north are the last in Wales to roll out the scheme.
They will work with staff from Betsi Cadwaladr University Health Board.
IFSS teams started work in Wales in 2010, providing support for families primarily with substance and alcohol use.
They also help those affected by domestic violence and mental health problems.
A review of pilot areas in Newport, Rhondda Cynon Taf and Merthyr, and Wrexham showed the service prevented 85 families from having their children taken into care.
Anglesey, Conwy, Denbighshire and Gwynedd councils, working with Betsi Cadwaladr University Health Board, are the last to introduce the scheme.
It means all Welsh local authorities, in partnership with their local health boards, now offer the service.
The Welsh government said the project was an example of the kind of partnership work outlined in its Social Services and Well-being (Wales) Bill, currently undergoing scrutiny by the Welsh assembly.
Gwenda Thomas, deputy minister for social services, said: "This is an excellent example of how integrating health, social services and the voluntary sector can help people with complex needs," she said.
"Substance misuse destroys families and it is often children who bear the brunt.
"To break the cycle in these families, over several generations in some cases, we must adapt the way services are delivered so parents are given the support they need to care for their children and look after themselves," she added.
A project which supports families whose children are at risk of being taken into care because of parental substance or alcohol misuse has been extended across Wales.