The fire broke out around 2:30 a.m. on the 2300 block of North Syndenham Street.
Relatives of the victim were seen coming and going Wednesday morning, as a restoration crew worked inside the home. They told Action News the victim was a man in his 60s.
Signs around the home indicate someone inside may have required the use of oxygen.
"(Firefighters) arrived and found the fire on a couple of floors of the building, a relatively contained fire," said Philadelphia Fire Commissioner Adam Thiel.
But firefighters soon discovered the victim's body.
Investigators have not officially identified the victim and said the fire marshal is working to determine the cause of the fire.
Commissioner Thiel said their work must continue, even while taking precautions as the country combats the rapid spread of COVID-19.
"Just a reminder for everybody as we deal with other things, our firefighters and medics are out here 24/7 continuing to perform our core mission and we want to remind everybody that fire is everyone's fight," said Thiel.
Thiel also said the adjustment during these times is requiring changes when it comes to installing smoke alarms inside the homes of those in need.
"You can still call 311 and if you need a smoke alarm, ask about those installations. 311 is still going on, we're not doing the installations right now because of the COVID crisis, but we are keeping all of them on file and we'll be out as soon as we can to install those smoke alarms," said Thiel.