She suffered a massive stroke after lung surgery earlier this week.
Fernandez leaves behind quite a legacy in Philadelphia. She served two terms in city council and was the first woman to run for mayor in 1999.
Along with city council, Fernandez also served 13 years as President of Moore College of Art and Design. She stepped down from her duties last year.
Philadelphia City Council President Darrell L. Clarke released the following statement regarding her death.
"Happy Fernandez had a personality and a heart befitting her name. My sadness at her passing is tempered by knowing her unique, sunny idealism has inspired countless others.
"I first came to know Happy when she was a Councilwoman and I was one of a crowd of young, anonymous staffers. Councilwoman Fernandez was always generous with her time and attention. Notably, she took the trouble to learn our names and always had a kind word.
"Councilwoman Fernandez will go down in Philadelphia history as the first woman to seek a major-party nomination for Mayor, and it is my sincere hope that more women follow in her footsteps. Happy was proof that idealism and a generous spirit are assets, not roadblocks, in civic life. May her passion for public education, for the young, and for the less fortunate live on across this City she loved so dearly.
"I extend my heartfelt condolences to her husband, Rev. Richard Fernandez, their sons and their grandchildren."