Edward Johnson was taken into custody in the 500 block of 69th Street.
They say Johnson does not have custody of his baby boy, but took him anyway.
When the two first vanished, police in Upper Darby were contacted by authorities in Allegheny County.
Police say they were able to track Johnson to his mother's home, in Upper Darby, using the GPS signal on his cell phone.
Authorities are working to reunite the baby with his mother.