William Carey, 46, has since been charged with first-degree murder, third-degree murder, and possession of an instrument of crime.
The incident happened at an apartment on the 500 block of Gravel Pike in Perkiomen Township just before 1:30 a.m.
State police say they were called to the scene after a 911 caller reportedly told a dispatcher that a woman was dead inside the home.
When troopers got to the apartment, 34-year-old Jessica Zipkin was found dead. Authorities say she suffered a fatal wound to the back of the head.
Police also said a hammer was found near her body at the scene.
Carey was arrested a short time later.
Officials said Carey and Zipkin were in a relationship but did not say what may have led to Zipkin's death.
Police did not release any further details. Carey is set to have a preliminary hearing on November 13.