A man has been charged with killing a three-month-old baby girl.

The baby was hospitalised with brain injuries after an incident at a home in Girrawheen on Friday March 12.

She was taken to hospital but died two days later.

Homicide Squad detectives originally charged the 30-year-old man with grievous bodily harm, but his charge is expected to be upgraded to murder when he faces court today.

The 30-year-old man from Girrawheen is expected to appear at the Perth Magistrates Court.