Although metal–sulfur batteries (M–S batteries, M = Li, Na, K) are promising next-generation energy-storage devices because of ultrahigh theoretical energy density, low cost, and environmentally friendliness, their practical applications are significantly hindered by the shuttle effect of polysulfides and growth of alkali metal dendrites. These issues can be mitigated by using Janus metal atomic-site catalysts, which possess the maximum atom utilization efficiency (≈100%), adjustable electronic structures, and tailorable catalytic sites, thereby effectively improving the electrochemical performance of M–S batteries. In this review, the recent progress and development of Janus metal atomic-sites on the properties, synthesis, and characterizations are reviewed. Then, the recent advances in Janus metal atomic-site catalysts intended for accelerating polysulfide conversion and regulating alkali metal deposition, briefly introducing the working principles of the Janus metal atomic-site catalysts in M–S batteries, are systematically summarized. Furthermore, a high emphasis is placed on effective regulation strategies for the rational design of Janus metal atomic-site catalysts in M–S batteries. Finally, the current challenges and future research directions are also presented to develop high-efficiency Janus metal atomic-site catalysts for high-energy M–S batteries.