The city's credit rating has been upgraded from "A" to "A+," with a long-term outlook of "stable."
Fitch cited Philadelphia's healthy general fund reserves, along with strong and consistent financial management.
It also said the continued improvement to the city's pension fund helped.
Credit ratings are a key factor in determining the interest rate the city pays on its infrastructure borrowing.
This rating action also comes ahead of Philadelphia's upcoming bond sale.
On Thursday, the city will price $100 million in bonds for the rebuild program, which invests in parks, recreation centers and libraries all across Philadelphia.