In May 2018, the island of Mayotte (Comoros archipelago) experienced a major seismo-volcanic crisis that was accompanied by effusive eruptions until 2021. This eruption is the largest eruptive event ever documented in the submarine domain, and has led to the birth of a new volcano, named Fani Maoré, on the East Mayotte volcanic chain. The extrusion of over 6 km3 of lava by this volcano has reshaped the submarine landscape and created new microbial habitats. A native sulfur-rich massif at the top of the volcano was sampled in 2021, and studied using metagenomic, phylogenomic, microbiological, chemical, mineralogical and petrological approaches. The sulfur-rich massif of this volcano hosts a diversity of microorganisms belonging mainly to the phyla Campylobacterota, Bacteroidota, Desulfobacterota and Pseudomonadota using organic and inorganic carbon sources and a wide range of electron donors and acceptors, which are mainly sulfur species. The relative importance of the 4 main catabolisms of the sulfur cycle (sulfur disproportionation, sulfur oxidation, sulfur reduction and sulfate reduction) expressed in culture at 3 temperatures and the dominant cultivable taxa associated with these catabolisms were also determined, and showed a greater cultivable abundance of cells under sulfur-oxidation and sulfur-reduction conditions. A conceptual model of the sulfur cycle in this sulfur-rich part of the volcano was proposed. In conclusion, the sulfur cycle appears to link the microbiome to biogeochemistry in the sulfur-rich deposit of this submarine volcano.