It happened around 8:30 p.m. on the 2600 block of North 33rd Street in the Strawberry Mansion section of the city.
At the scene, police found a woman in her 50s suffering from a gunshot wound to the chest and stomach. She later died at the hospital.
Police confirm the victim's brother was arrested in the murder.
Anyone with any information is asked to police at 215-686-TIPS.