Polychaetes larger than 500 micrometers collected from 63 sites in deep-water of the southwestern Gulf of Mexico were analyzed. Each site was sampled once a year during four consecutive years (2015-2018). A wide geographic area was sampled (92.7° to 96.7° W and 18.7° to 23.0° N) in a large depth range (185 to 3740 m). The sites were grouped in one of three depth categories (DCs), upper bathyal zone (UBZ, 185-1499 m), lower bathyal zone (LBZ, 1500- 2999 m), and abyssal zone (AZ, 3000- 3740 m). We carried out a regional analysis adding the abundances registered in each site during the four samplings. Environmental variables values were averaged in the four years. Abundance, alpha, and beta taxonomic diversity patterns were evaluated. Dissolved oxygen, salinity, and temperature in bottom water showed a variation between 185 and 1200 m but were stable in deeper zones. Variables measured in sediment characterized AZ by higher values of carbonate, whereas UBZ recorded higher content in aromatic hydrocarbons, organic matter and silt. A total of 1968 specimens belonging to 45 polychaete families were collected. We reported the bathymetric distribution, and abundance depth-related pattern for each family. Multivariate analysis showed depth-related shifts in the polychaete community structure. The highest taxonomic diversity was recorded at intermediate depths. Latitude, depth, and silt content were the drivers of the polychaete community. The seasonal analysis showed variations in the sediment composition and polychaete abundance. The most related abiotic variables with fauna distribution were latitude during spring and depth in summer.