The campaign, which includes a video produced by youth marketing agency Livity, highlights the "barrage" of negative voices girls are exposed to through the media.
The film depicts girls in a series of apparently positive scenarios, but as they develop, voiceovers from a variety of media and entertainment personalities, including John Inverdale, Joey Essex and Katie Hopkins, force viewers to think again.
Watch the film below to see how it plays out:
According to Girlguiding, the campaign targets women aged 25-34, with the aim of encouraging them to volunteer for the charity and provide a role model for young girls - particularly those aged 11-21, who, in 70 per cent of cases, are exposed to sexism so often it affects most areas of their lives, research by the charity found.
Commenting on the campaign, Girlguiding communications director Becky Hewitt said: "#ForTheGirl highlights the level of sexism and inequality girls face in their day-to-day lives and via the mainstream media, and reminds them they don't have to accept it.
"We are calling on everyone to join girls in challenging sexism whenever and wherever they see it - to build a fair future for girls everywhere."
The film launches at 2pm today (3 November) on Unilad's Facebook page, as well as a number of other platforms.