BRB stands for:
- "Be right back", internet/chat slang, also sometimes treated as a synonym of "bathroom break"
- The Beatles: Rock Band
- Buckling-Restrained Braced Frame, a specialized earthquake bracing system. See BRBF and Buckling Restrained Brace
- Bank of the Republic of Burundi or Banque de la République du Burundi, the official name in French of the central bank of Burundi
- Bayerische Regiobahn, a train company in Bavaria, Germany
- Benefits Review Board, a part of the United States Department of Labor
- Big red button, a type of command button
- Birmingham Royal Ballet, a ballet company
- Blaire Reinhard Band, a New Jersey rock band
- BRB Internacional, a Spanish animation studio.
- Brienz Rothorn Bahn, a Swiss railway
- Brigade de répression du banditisme, a special police unit of the French Ministry of the Interior.
- British Railways Board, the former governing body of British Railways
- BRB (Residuary) Ltd., its successor
- BRB, the ISO 3166-1 3-letter country code for Barbados
- BRB, the car number plate for Brandenburg an der Havel
- The blood-retinal barrier, cells in the eye that prevent certain substances from entering the tissue of the retina