Hoyer was born in New York City but grew up in Mitchellville, Maryland. He graduated from Suitland High School in Suitland, Maryland and went on to attend the University of Maryland, College Park, earning a B.S. degree in 1963. He earned his law degree from Georgetown University in Washington, D.C. in 1966. He and his deceased wife, Judy Pickett Hoyer, have three daughters: Susan, Stefany, and Anne.

In 1966 at the age of 27, Hoyer won a seat in the Maryland State Senate. In 1975, at the age of 35, Hoyer was elected President of the Senate, the youngest in state history.

In 1981, Hoyer was elected to the House of Representatives by special election to succeed the ailing Gladys Spellman from the fifth congressional district of Maryland. He is now the longest-serving House member from Southern Maryland in history, as well as the highest-ranking member of Congress in Maryland history.

Hoyer has served as Chair of the Democratic Caucus, the fourth-ranking position among House Democrats, from 1989 to 1994; the former Co-Chair (and a current member) of the Democratic Steering Committee; and as the chief candidate recruiter for House Democrats from 1995 to 2000. He also served as Deputy Majority Whip from 1987 to 1989. On November 14, 2002, Rep. Hoyer was unanimously elected by his colleagues in the Democratic Caucus to serve as the House Democratic Minority Whip, the second-highest-ranking position among House Democrats.

In Congress, Steny Hoyer has built a reputation as a defender of Federal employees and a leader on education, human and civil rights issues. He is perhaps best known for serving as the lead House sponsor of the Help America Vote Act, which President Bush signed into law on October 29, 2002, and for sponsoring the passage of the Americans with Disabilities Act of 1990 when Tony Coelho was forced to resign.

Hoyer currently serves on the following U.S. House committees: