The 22-year-old was found at the bottom of a stairwell at 12:50 am on Saturday, Thames Valley Police said.
She was discovered in the Millennium Madejski Hotel, which forms part of the English Premier League side’s ground. Reading lies 40 miles (60 kilometers) west of London.
The woman was pronounced dead at the scene.
“The woman had been attending a Christmas party at the time of the incident,” said Detective Inspector Phil O’Neil.
“We are treating her death as unexplained and there are a number of inquiries taking place to establish the full circumstances of what happened.”
No arrests had been made, he added.
Reading played away from home against champions Manchester City on Saturday.