The aims to help girls through puberty by offering advice on a range of sensitive issues, from periods and pre-menstrual tension to first boyfriends.
The magazine-style site, created by integrated agency Arc London, goes live this week and is similar to the beinggirl.com portal P&G has set up in the US.
Beinggirl.co.uk will be promoted through online and press advertising and direct marketing activity. Arc will work alongside sister agency Leo Burnett on ads.
Jennifer Sofia, P&G Femcare's interactive marketing manager, emphasised that the site would be "relevant to UK teenage girls".
P&G's feminine care range includes Always and Tampax. In the summer, P&G's marketing director of paper, Gino De Jaegher, who is responsible for the brands, replaced Gill Whitty-Collins as UK marketing chief of P&G's beauty business. He retains control of its femcare brands.
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