Fields was born in Port Allen, Louisiana, and received his undergraduate and law degrees from Southern University in Baton Rouge.

Fields was elected to the State Senate in 1997 and re-elected in 2003, then running unsuccessfully for the Louisiana Public Service Commission in 2004.

On January 23, 2024, Fields announced a campaign to return to Congress after court-ordered redistricting gave Louisiana a second Black-majority and Democratic-leaning seat.

[5] While still in law school, Fields began his first campaign for Louisiana State Senate, doing most of the organizational work himself and writing his own jingles for radio commercials.

To the surprise of some experts, he unseated Turnley, who in the Commercial-Appeal referred to Fields as "a very ambitious young man and an astute campaigner.

He was forced into a runoff against fellow state senator Charles D. Jones of Monroe, which Fields won with more than 73 percent of the vote.

Meanwhile, progressive interest groups such as the National Abortion Rights Action League, PeacePAC, and the American Public Health Association, as well as a range of labor-affiliated organizations, gave him a perfect rating.

His efforts as a legislator often involved channeling funds into education and protecting consumers from the excesses of insurers, banks, and other such institutions.

Many in his party were angered by his candidacy, since most felt that a black challenger could not seriously win the office and Mason-Dixon Polling released on October 17, 1995 showed Fields to be the loser in every possible head-to-head combination of candidates.

[citation needed] He narrowly beat the top two white Democratic candidates in the primary and made it to a runoff with Republican Mike Foster.

Foster's conservative message, designed by media consultant Roy Fletcher, who also had handled Cleo Fields' campaign for Congress, resonated with Louisiana's voters, who in a previous election had given former Ku Klux Klan leader David Duke nearly 40 percent of the popular vote.

[citation needed] During this race Fields began a feud with fellow Democrat Mary Landrieu who did not endorse him in the second round.

On October 12, 2019, Fields was re-elected to the 14th senatorial district, making history again by becoming the first person in Louisiana to return to the Senate for the third time.

In 1997, Fields was caught on an FBI surveillance tape stuffing about $20,000 in cash in his pockets after accepting it from then Governor Edwin Edwards.

[8] It was later revealed that Fields had abused his congressional franking privileges by sending newsletters to his district, at a cost of about $46,000, paid for by taxpayers, that were used for his gubernatorial bid.

[14] At the time, Fields stated that the incident was just an innocent business transaction between friends, and said there was a humorous explanation, which he would make public shortly thereafter.

At the "State of the Black Union 2008" symposium in New Orleans, Louisiana in February 2008, Fields said, "Rosa Parks sat down so we could stand up.