The online survey also found that 16% of people are either unsure or are already aware that they are using an unsecured network.
Researchers noted that nearly 50% of home users with security installed systems never change their network password, and a further 13% didn't know if they did or not.
As a result of its findings, the ICO is calling for internet operators, retailers and manufacturers to raise their game when it comes to advising new users of WiFi systems about the security that is needed.
The ICO has also published new guidance on WiFi security, and how to change the setting on a modem to make it more secure.
Steve Wood, head of policy at the ICO, said that people would not go out and leave their front door unlocked, but many are still surfing the internet without adequate protection for their personal information.
"The fact that Google's Street View cars were able to pick up payload data from unsecured WiFi networks as a by-product of their signals mapping exercise has further highlighted that more people need to take their Wi-Fi security settings seriously", he said.
"Leaving your WiFi connection unsecured allows people easy access to your network. This increase in traffic could reduce the speed of your connection or cause you to exceed a data cap imposed by the service provider", he added.
Wood went on to say that this also leaves users open to the actions of rogue individuals who may be using your WiFi to carry out potentially criminal actions without your knowledge.
"Today's new guidance aims to get people thinking about whether they are doing enough to ensure their wireless networks are secure", he said.