The NSPCC and O2 polled mothers and fathers with youngsters aged eight to 13 and found that less than a fifth of parents are having frequent conversations with their children about staying safe online.
Justin Humphreys, Executive director of safeguarding at Churches' Child Protection Advisory Service told Premier that a parent having a chat with their offspring wasn't enough to protect them from the internet's potential danger.
He said: "It should be a frequent conversation - speaking with your children in an age-appropriate way, giving them permission to ask questions about things that concern them.
"We just need to be speaking about it as much as we might speak about other everyday things."
The NSPCC and O2 have launched a campaign called Share Aware to help "parents untangle the web" and "teach their children to be share aware."
In an animation created by the organisations, the voice of comedian Catherine Tate is used to illustrate that children don't always know how to be safe online.
Tate, a mother-of-one, said: "As a parent you teach your child how to cross the road and warn them about 'stranger danger' but it can be harder to know how to keep them safe online - especially when the speed with which new apps and games appear outwits even the best of us.
"The NSPCC and O2's Share Aware campaign is a bit of a life-saver because it helps parents get to grips with all that Snapchatting, Whatsapping, and video-chatting and it makes chatting about their life online easy.
"It's a simple guide on how to teach your child to stay safe online and it does all the hard work for you."
The children's charity also found that although eight out of ten parents in a YouGov poll said that they knew what to say to their child to keep them safe online, only 28 per cent had actually mentioned privacy settings to them and just 20 per cent discussed location settings.
Claire Lilley, head of child online safety at the NSPCC, said: "Parents are the first point of call for a child when it comes to staying safe in real life and this is no different when it comes to their online life.
"Talking to your child and exploring their online world with them is the best way to keep them safe, but it can be hard to keep up to speed with the internet and some topics can feel more difficult than others."
While the internet, social networks, apps and games can be challenge children's safety, Humphreys said Christian parents shouldn't stop their children from using them.
He added: "The most effective way to deal with it is to accept that it is there, to educate ourselves as best we can about both the benefits and the risks of online activity and to seek to engage our children and young people in meaningful regular dialogue about those issues."
Listen to Justin Humphreys, Executive director of safeguarding at Churches' Child Protection Advisory Service speaking with Premier's Eno Adeogun here: