Edge passivation for tuning magnetism of zigzag MoS2 nanoribbons (ZMoS2NRs) is proposed. Edge passivation can tune ZMoS2NRs from nonmagnetic metal to ferromagnetic metal. When either edge is passivated, the systems exhibit single-edge ferromagnetic states. These findings may inspire great interest in the community of ZMoS2NRs and motivate numerous experimental researches.