A raft of measures to protect children from 'sexualisation' are set to be unveiled, as retailers agree to restrict the sale of inappropriate clothing to youngsters.
Mothers' Union chief executive Reg Bailey will publish his recommendations in a Government-commissioned review.
The British Retail Consortium has also launched new guidelines, in response to demands for restrictions on inappropriate children's clothing - including lace lingerie and push-up bras.
Nine stores - Asda, Debenhams, Argos, John Lewis, Next, Marks & Spencer, Peacocks Sainsbury's and Tesco - have signed up with others being urged to participate.
Mr Cameron has backed moves to make it easier to block adult content on mobile phones, ban raunchy billboard posters near schools and bar the use of youngsters to market products.
And he said he would summon retailers, advertisers, broadcasters, magazine editors, video games and music industry chiefs and regulators for a summit in October to discuss progress.
Under the changes proposed by Mr Bailey, steamy pop videos would be restricted to older teens and later television slots and magazines featuring sexualised images covered up on shelves.
An option to request adult material be barred from any new home internet service, laptop or mobile phone should also be introduced and parents given more say in the TV watershed guidelines.
Mr Bailey said he hoped his review would help tear down the sexual "wallpaper" surrounding today's young people and give parents a stronger voice in regulation.
Welcoming the report, Mr Cameron told him in a letter that it represented "a giant step forward for protecting childhood and making Britain more family-friendly".
While ministers would examine the recommendations, most required action from business and regulators who would have to be held to account "in a transparent way", he said.
Mr Cameron said he was particularly keen to see rapid progress on a centralised online tool for parents to report inappropriate material or products.
"This not only seems entirely sensible, but also relatively easy and simple to introduce.
"I see no reason why the website cannot be up and running in good time to get feedback from parents for our October meeting," he said.
The six-month review took evidence from more than 2,000 parents and 500 young people as well as 120 separate organisations.
Mr Bailey said: "Regulators, businesses and broadcasters should do more to connect with parents - it's not enough for them to work out what is acceptable from what people complain about afterwards.
"I hope that they see that it's good business if you look out for families. Then we can all help to make Britain a more family friendly place."