The delivery driver was making stops along the 4300 block of Tackawanna Street in the city's Frankford neighborhood.
That's when police say an armed masked man tied up the driver with a belt and drove the truck a few blocks to the 1600 block of Womrath Street.
The suspect was able to get away with a couple of packages.
The driver was not injured.
FedEx manager John Suarez says he spoke with the victim right after the incident.
"When he called me, he was in a really low voice. So I'm not sure if the guy was outside the truck, but he told me to call 911 and sent me his location," said Suarez.
No arrests have been made.
Anyone with any information is asked to call police at 215-686-TIPS.