A bicycle derailleur includes a base member, a movable member, a link member, a chain guide, a biasing mechanism and a switching member. The link member movably couples the movable member to the base member. The chain guide is pivotally coupled to the movable member about a pivot axis. The biasing mechanism is operatively disposed between the movable member and the chain guide, and biases the chain guide with respect to the movable member about the pivot axis in a first direction in a biasing state. The switching member is configured to selectively switch the biasing mechanism between the biasing state and a releasing state. The biasing mechanism biases the chain guide less in the releasing state than the biasing state. The switching member is disengaged from the biasing mechanism in the biasing state. The switching member is engaged with the biasing mechanism in the releasing state.