The Central Neutron Detector, a recently constructed scintillator barrel which is used in CLAS12 at Jefferson Lab to detect 0.2–1 GeV neutrons at backwards angles, is here described. The motivations and R&D tests leading to its final design, based on three radial layers of coupled paddles with one-side light readout by photomultipliers plus “U-turn” lightguides on the other side, are outlined. The performance of the detector, evaluated from cosmic-ray tests and simulations, which satisfies the physics requirements, is reported.