Two animation-style TV ads will air from New Year's Day for five weeks, illustrating the transformative effects of the charity's work.
One features the story of Nicola, a young carer whose mother was diagnosed with MS when she was eight years old, so she began looking after her. This affected her ability to get involved with school and her self-confidence.
With Action for Children's support, she says was able to cope, and says she has "become a different person".
The other, airing from mid-January, features the story of Dan, who is on the autistic spectrum and as a result has struggled with his ability to interact with other people and control his temper.
Through his attendance at an Action for Children school he became able to change his behaviour and feel more at peace with himself.
Nicola, who is now in her 20s, and Dan, now 18, provide the voiceovers for their respective stories, which end with the charity's ‘As long as it takes' strapline. Ads will also appear in print
Explaining the campaign, a spokeswoman said: "We have been Britain's best-kept secret - a massive charity with a muted campaigning voice. We want to establish the organisation as a fearless campaigner."
The campaign will be followed up by research among six- to 13-year-olds to identify the support they need.
The charity, which is 140 years old in 2009, rebranded from NCH in September.
