Fiol was born in Rio Piedras, Puerto Rico and is the second woman in Puerto Rican history to serve in the highest court of the island as well as being the second woman to hold the post of chief justice.
Fiol received her law degree from the University of Puerto Rico School of Law, magna cum laude, and later her master's and doctorate degree in Juridical Science from Columbia University.
She held that seat until 2003, when Governor Sila Calderón appointed her to associated justice for the Puerto Rico Supreme Court.
On April 11, 2014, Fiol Matta became the 16th chief justice of the Supreme Court of Puerto Rico, after being nominated by Governor Alejandro García Padilla, thus succeeding Federico Hernández Denton as court chief justice.
Justice Fiol Matta was perceived as the leading liberal voice in the Puerto Rican high court.