The Japanese electronics giant said 25,905 units had been shipped globally since they went on sale in February.
It said it may recall the computers but was so far asking customers to stop using them, adding that it plans to issue more details, including repair options, over the next couple of weeks.
"There is a risk that battery overheating could damage part of the computer," it said in a statement.
"We're asking customers to stop using their PC immediately, unplug the cable and stop using it."
The computer's lithium-ion batteries were produced by Sony rival Panasonic.
The Vaio Fit can be adjusted to turn it into a tablet computer as well as traditional laptop.