GCB may refer to:
- GCB (TV series) (formerly titled Good Christian Belles), a 2012 American television series based on the book Good Christian Bitches by Kim Gatlin
- Gaming Control Board, any governmental body that regulates gambling in its jurisdiction
- Generator circuit-breaker, a special circuit breaker in the high-current connection between generator and generator transformer
- Ghana Commercial Bank
- Gloucestershire Cricket Board
- Glucocerebrosidase, an enzyme
- (Dame/Knight) Grand Cross of the Order of the Bath
- Great chain of being, a western medieval concept of the order of the universe
- Grilled Chicken Burger, sold by McDonalds in Malaysia in 2010–2011