Manufacturers said more and more items -- from ovens to cars -- were now able to integrate thanks to better wireless technology, offering convenience and the chance to save energy.
More than 600 companies are showcasing cutting-edge gadgetry at this year's Combined Exhibition of Advanced Technologies (CEATEC) in Makuhari, near Tokyo.
One of the highlights is "smart innovation" which connects home appliances -- from washing machines and air conditioners to security cameras at the door -- to mobile devices.
"You will soon be able to use your smartphone or tablet PC as if it is a remote control for all these appliances," said Shuji Tomaru of Japanese mobile phone carrier NTT DoCoMo.
"If somebody tries to break into your house, you would immediately know because your phone will receive the information."
Residents, he said, could also use their phone to switch on the air conditioner before they return home or to turn on a washing machine.
Panasonic, which has already unveiled rice cookers and washing machines that can be controlled from a mobile phone, was Tuesday demonstrating bathroom scales and blood pressure-measuring devices connected to the Internet.
Masaki Matsukura at the company's booth said that in ageing Japan, where grown children often live far from their parents, these devices can provide reassurance.
"They can be used when you want to check on your father's health condition, for example," he said. "You can see the medical data whenever he measures his blood pressure, no matter where you live."
Japanese car giant Toyota used its first appearance at CEATEC to show off its new Smart Insect car.
These small electric vehicles can recognise their driver and can be programmed only to operate if they know the person behind the wheel.
And in a move apeing the gestures that are becoming increasingly familiar as the use of tablet computers spreads, the car will do things like open its door at the wave of an arm.
"The Smart Insect is a car which can communicate with you, your home and society," said Toyota's Shigeki Tomoyama.
"You can tell it what you want by making gestures, and the car understands you and will adapt to your personal style.
"We like to think of it as a well-trained pet or a friend who understands you very well."
CEATEC runs until Saturday.