The assault happened around 10:30 a.m. on the 900 block of Meadow Lane.
According to the Delaware County District Attorney's Office, Officer Michael Tierney responded to the area after the suspect, Lawrence Crews, allegedly kicked in the door of his girlfriend's home on W. 6th Street.
"While responding to a call for a domestic burglary, Officer Michael Tierney approached the suspect and was completely senselessly attacked," Delaware County District Attorney Tanner Rouse said.
Rouse said Tierney attempted to detain Crews when the encounter escalated.
"The suspect at that time just started punching him, got him to the ground, there was a struggle for his Taser. Officer Tierney was struck by the Taser, in effect pistol-whipped with his own Taser," Rouse said.
He said Crews "pounced with closed fists" and repeatedly punched the officer in the face.
Emergency radio traffic captured first responders reporting that the officer suffered head injuries.
"He's got lacerations to the head - it looks like he was assaulted," a responding officer said.
Video from a witness on the scene showed police taking Crews into custody a short time later.
Neighbor Sharava Green said the incident left residents shaken.
Chopper 6 over incident that left police officer injured in Chester
"It's devastating and scary," she said. "I've never seen anything like this before until today."
Tierney was taken to the hospital with cuts to his head. Authorities said his injuries are not considered life-threatening and he is expected to recover and be discharged on Tuesday.
"We are grateful that our officer's injuries are not life-threatening and that he is expected to recover," Chester Mayor Stefan Roots said. "The safety and well-being of our police officers remain of utmost importance."
Investigators said Crews was also taken to the hospital as a precaution. His mother told Action News that he had recently been released from the hospital and struggles with mental health issues.
"This clearly was not somebody who was in their right mind," the district attorney said.
Crews is expected to face charges including aggravated assault on a police officer and burglary.
The district attorney said authorities are still piecing together exactly what led up to the assault, but called the incident preventable.
"We could've avoided this," Rouse said. "We don't have the facilities, we don't have the wherewithal, we simply don't have the will to get to someone with mental health issues before it escalates to this point."
Authorities also noted Tierney was recently among officers responding to a separate Chester incident involving gunfire.
"He's been through a lot this month and has seen a few scary incidents. He was banged up, he was shaken up, it was wild and it was unprovoked, and he's OK, he's not badly injured but that isn't for lack of trying."
Crews has been arrested three other times since 2015 for similar offenses, including another alleged attack on police.