Cardiss entered the 93rd Congress in 1973 after winning a special election to fill the vacancy left by the death of her husband. She soon established herself as an effective representative in her own right and  served until 1997. Throughout her congressional career she took special interest in the social and economic issues important to her district on Chicago's West Side.

Collins was born Cardiss H. Robertson in St. Louis, Missouri, on September 24, 1931, and moved to Detroit at the age of ten. After graduating from the Detroit High School of Commerce, she moved to Chicago to attend Northwestern University. Collins began work as a secretary for the Illinois Department of Labor and soon thereafter for the Illinois Department of Revenue. She worked with the Department of Revenue as an auditor until her election to Congress.

A keen interest in politics led Collins into involvement with the Chicago Democratic establishment, and she became committeewoman of the city's Twenty-fourth Ward Regular Democratic Organization. She was actively involved in her husband's campaigns as alderman, committeeman and congressman. After George Collins died in a plane crash near Chicago's Midway Airport in 1972, Cardiss Collins handily won the special election to fill his seat on June 5, 1973.

Beginning with her first term in Congress, she served on the Government Operations Committee, where she was chair of the Subcommittee on Manpower and Housing and was chair of the Subcommittee on Government Activities and Transportation. In this position Collins gained national attention for her investigations of airport security and advocacy of air safety issues. She also served on the Committee on International Relations (later Foreign Affairs) and sat on the Energy and Commerce Committee. She was a member of the select Committee on Narcotics Abuse and Control. As a Democratic whip-at-large, she was both the first black and the first woman to hold such a position. In addition to her political career, Collins is an active member of various civic organizations.

Collins has received awards for distinguished service from Roosevelt and Loyola Universities in Chicago and from the Congressional Black Caucus.

In 1996, she chose not to be a candidate for reelection and now lives in Alexandria, Virginia.