Barreiro was first elected Miami-Dade County Commissioner representing District 5 in June 1998. He was reelected to the District 5 seat on August 31, 2004.  His Commission district includes portions of the Cities of Miami and Miami Beach, as well as the communities of Little Havana, Downtown, and South Beach.

Elected to the Florida House of Representatives in 1992, Barreiro represented District 107 until his election to the County Commission.  While serving in the House, he chaired the Tourism Committee and served on the General Government Appropriations and Long Term Care Committees.

In 1999, Barreiro sponsored a resolution for the creation of the Golden Passport to provide free transportation for Miami-Dade senior citizens.  More than 160,000 residents, 65 years old and older or Social Security beneficiaries, participate in this program.

In 2002, Barreiro chaired the Transportation, Infrastructure and Environment Committee and sponsored a resolution for a one-half cent sales tax to improve mass transit services as outlined in the People’s Transportation Plan (PTP.)  Prior to the passage of the PTP, Miami-Dade Transit (MDT) operated 705 buses.  Since then, MDT has increase the fleet to 1002 buses.

As Commissioner, he has served as chairman of the Miami-Dade County General Obligation Bond Committee, the Office of Public Transportation Management Subcommittee, and as chairman and vice chairman of the Internal Management and Fiscal Responsibility Committee.  Barreiro also serves as chairman for the South Florida Regional Transportation Authority, the Miami-Dade Metropolitan Planning Organization and is an honorary member of the Miami Yacht Club.

Barreiro is an active member of the community.  He has been recognized by many local, state, and federal organizations.  He is also an active participant as member of the following organizations: Greater Miami Chamber of Commerce; Miami Beach Chamber of Commerce; Elephant Forum; Miami Project to Cure Paralysis; National Rifle Association of America; Sierra Club; Dade Heritage Trust; UNIDAD; United States Holocaust Memorial Museum; Coral Gables Chamber of Commerce; Downtown Bay Forum; Transportation Steering Committee; and the Florida Association of Licensed Investigators.

Barreiro attended the University of Miami in Coral Gables, Florida and is the president of BABJ Investment Corporation in Miami, Florida.

Barreiro is the son of Cuban immigrant parents and was born in Clearwater, Florida in December 1965.  He has been married to his wife Zoraida for 11 years, they are the proud parents of two children.