It happened in the 4600 block of Fairmount Avenue just before 6:00 p.m.
Police say someone opened fire on the man, striking him in the leg and abdomen.
He was rushed to the Hospital of the University of Pennsylvania with unstable vital signs.
Police say a 40-year-old suspect was taken into custody near 38th and Wallace Streets a short time later after a foot chase.
They have not recovered a weapon.
The shooting is under investigation.
Anyone with information is asked to contact Philadelphia Police.