RLB may refer to:
- Raiffeisenlandesbanken, co-operative banks in Austria
- Railroad Labor Board, arbitrated labor disputes in 1920s United States
- Reconciliation and Liberation Bloc, Iraqi political party, 1995–2008
- Rider Levett Bucknall, a British-based global construction company
- Reichsluftschutzbund, air raid protection organisation in Nazi Germany
- Rebecca Long-Bailey (born 1979), British politician
- Régis Le Bris (born 1975), French football manager