The brief is to encourage applications for jobs manning the charity's phone lines, following company research that showed only one in four children who called Childline actually got through to speak to somebody.
The account was handed to Quiet Storm without a pitch. The charity has run poster and press campaigns, produced in-house, in the past.
Sangeeta Sharma, the new-business director at Quiet Storm, explained: "Childline said it was confident enough with the ideas we put forward that it didn't need to see anybody else."
She added: "The television work, which will be aired by the end of summer, will be based around drawing people into working for the charity."
The creatives working on the project will be Lee Ford and Dan Brooks, the creative duo who gained notoriety earlier in the year when a spoof Volkswagen ad they created, which featured a suicide bomber, made its way on to the internet and was circulated.