Mangrove is among the most carbon-rich biomes on earth, and the role of viruses in modulating local and global carbon cycling has been extensively implicated. However, few viruses have been isolated from mangrove sediments to date. We reported the isolation of a novel Bacillus phage (named as phage vB_BviS-A10Y) from mangrove sediments. Phage vB_BviS-A10Y had a hexameric head with a diameter of ~79.22 nm and a tail length of ~548.56 nm, which were typical features of Siphoviridae . vB_BviS-A10Y initiated host lysis at 3.5 h post infection with a burst size of 25 PFU/cell. The genome of phage vB_BviS-A10Y was 162,435 bp long with 225 predicted genes, and the GC content was 34.03%. A comparison of the whole genomes of phage vB_BviS-A10Y with known phage genomes in the IMG/VR database showed that phage vB_BviS-A10Y had the highest similarity (73.7%) with Bacillus phage PBC2. Interestingly, abundant auxiliary metabolic genes (AMGs) were identified in vB_BviS-A10Y genome. The presence of β-1,3-glucosyltransferase gene in phage genome supported our previous hypothesis that mangrove viruses may directly manipulate carbon cycling through their encoded carbohydrate-active enzyme (CAZyme) genes. Therefore, our study will contribute to the better understanding of the diversity and potential roles of viruses in mangrove ecosystems.