Police and paramedics were called to reports of an assault at a care home in Catford, southeast London, at about 12.40am on Monday.
A woman, aged in her 90s, was taken to hospital where she later died.
The same day, a man in his 60s was been arrested on suspicion of murder and taken to a south London police station.
Both were residents at the care home in Canadian Avenue, police said.
Alexander Rawson, 62, has been charged with murder and is expected to appear in custody at Bexleyheath Magistrates’ Court on Tuesday.
The victim’s next of kin have been informed of her death and are being supported by specialist officers.
Police said a post-mortem examination will take place to establish the cause of death.
The Metropolitan Police said in a statement: "Police were called at around 00.40hrs on Monday, 4 January, to a report of an assault at a care home in Canadian Avenue, Catford.
"Officers attended along with London Ambulance Service.
“A woman, aged in her 90s, was taken to hospital where she later died."