The detached garaged on Exchange Street, Hyde Park, caught fire at around 12.35am, with firefighters called out to fight the blaze.
Fire engines were sent to the scene from both Doncaster and Edlington fire station, and were dealing with the incident for an hour.
Firefighters across South Yorkshire are asking the public to help them crack down on deliberate fires across the county, by reporting incident details to a dedicated new fire line.
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FireStoppers, which works in the same way as Crimestoppers, allows the public to anonymously report any information they have on deliberate fire-setting, by calling a dedicated phone number, 0800 169 5558, or by using an online form – www.firestoppersreport.co.uk. Once reported, the details will be anonymised and used as part of fire and police investigations.
Doncaster saw 1,116 deliberate fires in the last year.