The print campaign by Bartle Bogle Hegarty, which appeared in The Times and The Daily Telegraph attracted two complaints from readers who found the use of language offensive.
However, the ASA decided that the use of language was in context because it was "intentionally hard hitting to reflect the realities of the situations Barnardo's workers had to regularly deal with".
The text of the ad says: "He told his parents to f**k off. He told his foster parents to f**k off. He told 14 social workers to f**k off. He told us to f**k off. But we didn’t. And we still haven't".
In its ruling, the ASA added that the AD was also unlikely to cause widespread offence because the readers of The Times and The Daily Telegraph are predominantly adult.
The ASA also noted that each of the papers asterisked out part of the word, with the Times using "f**k" and the Telegraph the even more toned down "f***".