A novel flame retardant (CuMoO4@h-BN) was synthesized through the co-precipitation method, and its structure and morphology were systematically characterized. CuMoO4@h-BN was added to polyurethane elastomer (PUE) to investigate the effect of thermal, flame retardancy and smoke suppression properties on the PUE composites. The results showed that 2 wt% CuMoO4@h-BN increased the residual char yield of the PUE composite notably to 9.8%. CuMoO4@h-BN exhibited an excellent charring effect. Compared with pure PUE, 2 wt% CuMoO4@h-BN decreased the peak heat release rate, total heat release and smoke density of the PUE composite by 73.6, 52.4 and 28.2%, respectively. CuMoO4@h-BN performed well in flame retardancy and smoke suppression. It may be attributed mainly to the physical barrier effect of h-BN and catalytic carbonization effect of CuMoO4. It is expected that this simple and inexpensive treatment of PUE may help expand the fire safety applications of the material.