Born Roberta Frances Horowitz in Santa Monica, California on April 22, 1937, Fiedler attended area public schools. Studies continued at Santa Monica Technical School (1955–1957) and Santa Monica City College (1955–1959).
Fiedler formed her political identity at Encino's Lanai Road Elementary School, where she mobilized other mothers to protest court-ordered busing. Fiedler formed an organization called Bustop in 1976, and the organization grew to 30,000 members in weeks. Valley activists rise up Fiedler's role in the grass-roots group helped propel her to public office, as she won a surprising upset in 1977 against Los Angeles school board president Robert Docter, who favored busing. While serving on the Los Angeles (City) Board of Education, Fiedler and fellow board member Roberta Weintraub were fierce opponents of forced busing.
In 1980, Fiedler ran as a Republican for Congress against Democratic James C. Corman, who had served 20 years in Congress. Fiedler was an underdog, running against Corman in a district that was 62% Democrat, and with the incumbent in line to be the next chairman of the House Ways and Means Committee. But in a year in which Reagan's coattails drew large numbers of Democratic voters to the G.O.P., the National Republican Congressional Committee targeted Corman, hoping not to defeat him, but to embarrass him. Busing was the central issue in the election between Fiedler and Corman. Time magazine reported on the campaign as follows: "Again the issue is local: busing that was ordered by the California Supreme Court in 1977 to desegregate public schools in Los Angeles County. The Congressman's opponent in the election, Republican Bobbi Fiedler, 43, mother of two children, has made a political career out of the issue. She used it to win a seat on the city's school board in 1977. She decided to run against Corman last year, when he refused to push for an antibusing amendment to the U.S. Constitution. He also declined to back California's Proposition 1, which limits the power of state courts to order busing and was approved by 81% of the voters in his district. Insists Fiedler: 'Corman is completely out of touch with the people in the district. He has voted for 31 pro-busing measures in Congress.' Replies the softspoken, white-haired Corman: 'I've never had anything to do with ordering school busing. That's done by the courts. But I believe that we have to comply with the law.' In addition to busing, Fiedler flays Corman as a big-spending supporter of wasteful social-welfare programs." Time magazine, Sept. 22, 1980, The House: Two Veterans Find Trouble Back Home.
Corman's campaign manager, Clint Reilly, later recalled that his candidate's position on racial integration drew heavy fire from Bobbi Fiedler, who he described as "the leader of LA's anti-busing movement." Reilly noted that the Republican Party raised more than a million dollars for Fiedler, and "the campaign was waged in the racially charged atmosphere of the San Fernando Valley." After a fierce campaign in which Corman was often picketed by anti-integration activists, the candidates entered election day in a dead heat in the polls, and Corman lost to Fiedler by 750 votes out of 200,000 cast.
Fiedler was the first Jewish woman elected to the Congress from California, being followed two years later by Barbara Boxer and later by Jane Harman. Fiedler considered herself an independent Republican, breaking with her party over her support for abortion rights and the Equal Rights Amendment.
Fiedler went on to upset Corman and as she was elected to the 97th Congress. After a narrow victory in 1980, Fiedler was reelected in 1982, defeating Democrat George Henry Margolis by a margin of 71.8% to 24.1%. She won in another landslide in 1984, defeating Charlie Davis by a margin of 72.3% to 25.9%.
In 1986, Fiedler did not run for reelection to the House of Representatives, opting instead to make an unsuccessful bid for the Republican nomination to challenge Alan Cranston for a United States Senate seat. She was charged with political corruption in January 1986 after an undercover investigation allegedly showed that Fiedler offered a rival, State Senator Ed Davis, $100,000 to withdraw from the Republican senatorial primary. The charges were dismissed by the court before the matter went to trial. Despite the dismissal of the charges in February 1986, Fiedler garnered only 7.2% of the vote in the Republican primary.
In 2001, Fiedler was one of the few San Fernando Valley leaders to flatly endorse the campaign for Valley secession from the City of Los Angeles.
Fiedler is currently a resident of Northridge, California.