The latest work, created by Ogilvy & Mather, is the third phase of the three-year campaign. The radio ads break this week with new online advertising created by Profero debuting in mid January.
An earlier film showing a middle-aged man on the internet but with his voice dubbed by a child will run in cinemas from February.
The ads encourage children to think twice about who they might be talking with in chat rooms and provide advice to help them stay safe on the internet and mobile phones.
Paul Goggins, Home Office minister, said: "The first two phases of our awareness campaign have been very successful with significant increases in the number of parents giving safety advice to their children and in the number of children who know not to give out their personal details online."
He added: "But we can not be complacent; we want to continue to do everything we can to make sure that children are aware that people are not always who they say they are on the internet."
The Home Office has also published a leaflet for parents called 'Keep your child safe on the internet'. It is available on a dedicated site .
Last year the government added a grooming offence to the Sexual Offences Act, meaning that meeting a child with the intention of committing a sex offence can be punished with a maximum of 10 years' imprisonment.
It followed high-profile cases of children snared by paedophiles including the disappearance of 12-year-old Shevaun Pennington with a 31-year-old former US Marine. Pennington was later found unharmed.
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