He is the son of a Polish-American mother and an Italian immigrant father who moved to Chicago and worked for the Pullman train car company.

He received a Pullman Foundation scholarship to attend the University of Illinois, where he studied political science and served as student body president.

He is a former Senior Supervising Attorney of the General Litigation Division for the Corporation Counsel for the City of Chicago, working with Mayor Harold Washington during the time of Council Wars.

[citation needed] In 2006 Fioretti was the attorney for LaFonso Rollins, a young African American sentenced to 75 years in jail for rape.

[citation needed] In 2022, Fioretti successfully represented Dolton, Illinois Mayor Tiffany Henyard in her lawsuit to block the certification of an attempted recall election against her.

[10] Fioretti had come into conflict with mayor Rahm Emanuel many times, including over siding with a successful resistance to Emanuel's efforts to move the water fee exemption for some nonprofits and religious groups in the city's budget and unsuccessfully opposing the licensing of rideshare companies such as Uber and Lyft.

Fioretti has attempted to improve the Chicago Public School system, working closely with administrators to solve issues both in and out of the classroom.

In 2008, Fioretti helped to create "Operation Safe Passage," an initiative designed to protect students on the way to and from school that coordinated the resources of the Chicago Police Department, the CTA, local faith-based institutions, and families.

In 2011, Fioretti won the "Defender of Public Education" Award from the Chicago Teachers Union, AFT Local 1 for his efforts at modernizing and sustaining neighborhood schools.

He supported the relocation of the United Airlines headquarters, bringing approximately 2,500 jobs from Elk Grove to Chicago.

Pete's Fresh Market, Target, and Costco have agreed to open new locations within the 2nd ward, providing food retailers and jobs to West Side residents.

That move was later challenged in court and Mayor Daley later withdrew the plan and the museum remained at Navy Pier.

[17] In November 2017, he announced that he would challenge incumbent Toni Preckwinkle for the Democratic nomination for President of the Cook County Board of Commissioners.

[19] Fioretti was one of several candidates challenging incumbent Cook County State's Attorney Kim Foxx in the 2020 Democratic primary.

Fioretti ran as the Republican nominee for President of the Cook County Board of Commissioners, once again challenging Preckwinkle, whom he lost to in the 2018 Democratic primary for the seat.

Fioretti ran against Democratic nominee Eileen O'neill Burke, a former judge of the Illinois Appellate Court who vacated her judicial position in order to run for state's attorney.