The 29-year-old man was held on suspicion of rape following an alleged sex attack on a 20-year-old woman at the Earl of Doncaster Hotel, Bennetthorpe, in the early hours of Monday.
South Yorkshire Police said a report of rape was made to the force some time between 3.45am and 4.45am on Monday.
The suspect has been released under investigation after questioning while enquiries continue.
A South Yorkshire Police spokeswoman said: "Officers investigating the reported rape of a 20-year-old woman in Doncaster have arrested a man in connection with the incident.
"Sometime between 3.45-4.45am on Monday, a report was made to police that the woman had been raped by a man at a hotel in Bennetthorpe.
"A 29-year-old man has been arrested on suspicion of rape and has since been released under investigation.
"The victim continues to be supported by specialist officers as enquiries into the incident continue."