That is nearly double the screen time found before the pandemic in similar children.
The results showed that children averaged 6.6 hours a day of media use. Contrary to previous research, weekday use (6.8 hours) was higher than weekend media use (5.8 hours).
"We found a high level of media use compared to what many experts think is appropriate for this age group," said lead author Rebecca Dore, from the Ohio State University.
"Some of that time spent using media was positive: watching educational videos and connecting with friends and family. But the amount of time they spent is something we should be aware of," she added.
The study was published online in the Journal of Developmental and Behavioral Pediatrics.
The team involved 151 low-income caregivers of kindergarteners in Ohio who completed online questionnaires between May 1 and June 30, 2020.
Caregivers responded to 12 questions assessing children's media use on the most recent weekday and weekend day. Media use included any kind of video, including television, movies or short clips on any electronic device, and using apps or games on any type of device.
The findings suggests parents might have been using media as a substitute for the time their children would have been spending in some type of child care that was closed because of the pandemic, Dore said.
Remote schooling didn't seem to be the main reason driving the results. Findings showed 84 per cent of children had direct contact with their teachers once a week or less, with 53 per cent reporting no direct contact.
Still, 61 per cent of caregivers reported their child was using media for learning more than usual, perhaps watching educational TV or using educational apps unrelated to formal schooling. Also, 47 per cent reported increased entertainment use, 45 per cent said there was more use as a way to occupy the child's time, 42 per cent reported increased use for maintaining relationships with remote family and friends, and 34 per cent said their child was spending more time using screens for family bonding.