Officials said the baby is being evaluated at St. Christopher's Hospital as a precaution.
Philadelphia police asked for the public's help in locating James Garrett, Jr. who family members said was last seen on Thursday with his father on the 5500 block of Spruce Street in West Philadelphia.
Police said the father was not being cooperative with officers.
The baby's family said Garrett had been primarily caring for the child with help from extended family.
No details about how the child was found were immediately available.