Almost half of parents who bought their children an internet-connected gadget for Christmas will not check who they are speaking to online, according to new research.
Barnardo's estimates that four million online-enabled devices were bought for youngsters over the festive period.
However, the children's charity found that just 55% of parents surveyed will monitor who they communicate with.
Plenty of child-friendly tech was expected to be in high demand in the run-up to Christmas, with new iPhone models from Apple and a new Xbox from Microsoft among the gadgets released just weeks before the festive season.
More than half of the devices bought – ranging from tablets to teddy bears – were bought for children aged 10 and under, but only 60% of parents plan on activating the maximum privacy settings designed to keep them safe.
For the charity's chief executive Javed Khan, the results of the survey are of huge concern.
"At Barnardo's we understand how vital the online world is to children, but also how the risks can damage their childhood," he said.
"Internet-connected devices like tablets and iPhones can also come in the guise of harmless dolls or teddy bears and potentially allow strangers to pinpoint your address, obtain your child's name and birthday, download their photograph and even listen in on your conversations.
"We're not saying don't buy or allow your children to enjoy these toys or devices, but we are urging parents and relatives to ensure their children are as safe as possible buy ensuring privacy settings are at maximum and that they monitor who their children are communicating with."
The plea comes after a similar warning was issued by consumer group Which? in November, with the product testing organisation having found a number of "concerning vulnerabilities" in "smart" toys tipped to be big sellers at Christmas.
Which? found that the likes of the Furby Connect and Toy-Fi Teddy were equipped with unsecured connections, meaning they can be accessed without a password, PIN code or any other authentication.
More from Internet safety
Anyone within 10m to 30m (33ft to 100ft) of Hasbro's Furby Connect can connect via Bluetooth when it is switched on, with no physical interaction required and no security measures obstructing the pairing process.
Barnardo's has urged parents to be cautious of devices that use Bluetooth, have speakers, microphones or cameras, and use GPS technology or request personal information during the set-up process.