In 2002, Mario Díaz-Balart was elected to the U.S. House of Representatives to represent Florida's 25th Congressional District, which covers portions of Miami-Dade County, Collier County, and Monroe County. In 2004, he was reelected to a second term with no opposition.

Díaz-Balart serves on the Budget Committee, the Transportation and Infrastructure Committee, and the Science Committee. In 2005, he helped deliver millions of federal dollars for I-75 widening project, Miami-Dade transit and hurricane relief for Florida while also pushing for responsible federal budget that keeps taxes low on hard-working families.

Díaz-Balart quickly made his presence known during his first term. He secured more than $52 million in federal money for southern Florida. He authored two amendments to protect Everglades restoration funding which were successfully passed. He successfully got FEMA to postpone implementation of new flood maps in Golden Gate. He was one of only a handful of freshmen to author and successfully pass stand-alone legislation and included legislative language in several bills that have been signed into public law. Additionally, Díaz-Balart helped found the Congressional Hispanic Conference and the Washington Waste Watchers, a group which combats government waste, fraud and abuse.

Before serving in the U.S. House of Representatives, Díaz-Balart served for 14 years in the Florida state legislature.  He was elected to the Florida House of Representatives in 1988 where he served until 1992.  In 1992, at age 31, Díaz-Balart became the youngest person ever elected to the Florida Senate. He was the first Hispanic to serve as Chair of the Combined Appropriations / Ways and Means / Finance and Tax Committee. During his time in the Florida Senate, he also chaired other important committees such as: Criminal Justice Appropriations; Banking and Insurance; and Children and Families. He was Vice-Chair of the Rules Committee.  In 2000, Díaz-Balart returned to the Florida House without opposition, where he served as Chair of the Congressional Redistricting Committee and Vice-Chair of the Procedural and Redistricting Council.

Díaz-Balart was consistently ranked among the most effective legislators in the Florida Legislature and was voted "Most Effective Legislator" by the Miami Herald in 1996. He developed a reputation as a budget hawk and supporting minority rights.  During his tenure in the state legislature, he sponsored the creation of law schools at FIU and FAMU and sponsored the Rosewood claims bill.  In 1992, Díaz-Balart sued for increased minority congressional representation.  In 2002, as a result of federal courts endorsing his lawsuit, three black and three Hispanic lawmakers from Florida were elected to Congress.

Congressman Mario Díaz-Balart was born in Ft. Lauderdale, FL, on September 25, 1961. He attended the University of South Florida in Tampa to study Political Science before beginning his public service career as an aide to then City of Miami Mayor Xavier Suarez in 1985.

Congressman Mario Diaz-Balart lives in Miami with his wife and son.