The threat was called in around 12:45 p.m. against Flight 777 from Shannon, Ireland.
The U.S. Airways jet landed shortly before 2:00 p.m. and was taken to a secure area to be searched.
The FBI, TSA and Philadelphia police searched the jet and eventually cleared the plane around 3:00 p.m.
In a statement, U.S. Airways said there were 171 passengers and eight crew members onboard the plane, a Boeing 757.
Everyone got off the plane safely, U.S. Airways said.
Philadelphia was the plane's intended destination.
Action News video showed the plane just after it landed as it was followed by a number of fire trucks.
After it stopped, the view from Chopper 6 HD showed some people coming down a walkway from the plane, which had a number of police vehicles nearby with lights flashing.
Operations at Philadelphia International Airport have returned to normal.