A television advertising campaign will support the appeal
A new base for ChildLine is to be opened in Edinburgh.
The NSPCC charity decided to establish the centre as part of plans to expand its service.
The launch of the Edinburgh operation is to be accompanied by a Scottish fundraising appeal, which the charity has said needs to raise £11m.
The money will allow ChildLine to develop new text and online services, and to recruit and train more volunteer counsellors.
The NSPCC has set itself the goal of doubling the capacity of ChildLine in Scotland by 2011.
'Care and support'
Elaine Chalmers, head of ChildLine in Scotland, said: "We need ongoing support from the public, businesses and others to make sure every child's cry for help is heard.
"One in three of the children who speak to ChildLine have told no-one else what is happening to them."
Minister for Children Adam Ingram will perform the official opening in Edinburgh, which is to be attended by ChildLine president, Esther Rantzen.
The NSPCC still needs to raise £11m
Mr Ingram said: "All children deserve care and support as they grow up and it's vital we listen to their fears and concerns.
"That's why the Scottish Government is proud to provide ChildLine with funding to help it expand services, open this new Edinburgh centre and support even more of our young people."
Over the past two years, the government has provided £55,000 towards the costs of setting up the Edinburgh base and expanding existing services in Aberdeen and Glasgow.
A further £228,000 has been provided for the year 2008-09.
ChildLine volunteers in Edinburgh started taking calls at the beginning of September.
One of the first volunteer counsellors was Adrian Mead from Leith.
"I've taken calls about abuse, bullying, family break ups, exam pressures, falling out with friends, homework, puberty, and pretty much anything the callers feel unable to discuss with parents, teachers or friends," he said.
"The support, fantastic training and the short time I have experienced as a counsellor so far has definitely enabled me to develop new skills and given me a real sense of doing something worthwhile."
The NSPCC has called its latest campaign for funds the "Child's Voice Appeal".
It is accompanied by television advertising which draws on the theme of voices being heard.
The charity also hopes to encourage adults who are concerned about a child to contact the NSPCC helpline.
Elaine Chalmers of ChildLine said: "It is important to remember that some children and young people are unable to contact ChildLine themselves, be it because they are too young, or too scared."