Sores form when people are stuck in one position for too long, which compresses the skin and cuts off the blood supply.
Canadian academics said that in a short trial on 37 people, the mild current mimicked fidgeting and prevented the sores forming.
Pressure sores are a common problem in hospitals around the world as patients are often too ill to get out of bed. Older people are at heightened risk because of poor circulation. Half a million people in the UK develop sores each year.
Doctors at the University of Calgary tested underwear which placed two pads of electrodes on each cheek.
Patients who were unable to move because of a spinal cord injury were zapped with 10 seconds of stimulation every 10 minutes for 12 hours a day.
The findings, presented at the Neuroscience 2012 conference, showed that none of the 37 patients developed a sore during the month long trial.
The researchers said the device mimicked fidgeting leaving people sitting in a slightly different position.
Robyn Rogers, a research nurse at the university, said: “Pressure ulcers can be terribly debilitating.
“Their incidence has not changed since the 1940s, indicating that the current methods of prevention simply are not working.
“Our hope is that this innovative, clinically friendly system will eventually make a difference in the lives of millions of people.”
The researchers said the pants were popular with nurses and patients, however, much larger studies would be needed to test how effective the underwear was at preventing bedsores.
Dr Peter Carter, the chief executive of the Royal College of Nursing, said: “Pressure ulcers, which can be prevented by good skincare, nutrition and regular movement, are not only very painful and distressing, they cost the NHS up to £2bn per year to treat.
“The expertise is out there, and good practice in many areas shows that money can be saved, not to mention the distress which can be prevented.
“All care settings need to make a concerted effort to make pressure ulcers a thing of the past, and if new technology can help and is cost-effective then nurses will welcome that.
“However, this must not be a substitute for having the right number of well-trained staff on a ward.”