Detectives believe the woman was violently assaulted in the bathroom of her ground-floor room at the Rosewood Court residential home in Shakespeare Close, Barkerend.
Police said the intruder searched drawers and cupboards.
Detective Superintendent Dick Nuttall said: "This is an appalling attack with violence being used towards a frail, defenceless lady.
"At this stage we believe the motive may be burglary but are keeping an open mind and would appeal to members of the public for any information.
"Incidents where intruders use violence against residents do not happen very often and we are making every effort to identify who is responsible as soon as possible."
It is believed that entry was gained through a window some time between 9.30pm and 10pm on Friday.
The victim was taken to Bradford Royal Infirmary, where her condition was described yesterday as stable. She is being supported by specially-trained officers and enquiries are being made to trace family members.
The area around the care home is used as a short cut between New Otley Road and Barkerend Road and police have appealed for anyone who saw something suspicious to contact them.
A care home spokesman said: "We are focused on looking after our residents and minimising the upset this incident has caused."
Neighbours were horrified by the crime. A woman in her 50s, who asked not to be named, said: "It's disgusting. Robbing an old lady, what can they gain?"