Oily bilge wastewater (OBW) is a hazardous hydrocarbon-waste generated by ships worldwide. In this research, we enriched, characterized and study the hydrocarbon biodegradation potential of a microbial consortium from the bilges of maritime ships. The consortium cZ presented a biodegradation efficiency of 66.65% for total petroleum hydrocarbons, 72.33% for aromatics and 97.76% removal of n-alkanes. This consortium showed the ability to grow in OBWs of diverse origin and concentration. A 67-fold increase in biomass was achieved using a Sequential Batch Reactor with OBW as the only carbon and energy source. The bacterial community composition of the enriched OBW bacterial consortium at the final stable stage was characterized by 16S amplicon Illumina sequencing showing that 25 out of 915 of the emerged predominant bacterial types detected summed up for 84% of total composition. Out of the 140 taxa detected, 13 alone accumulated 94.9% of the reads and were classified as Marinobacter, Alcanivorax, Parvibaculum, Flavobacteriaceae, Gammaproteobacteria PYR10d3, Novispirillum and Xanthomonadaceae among the most predominant, followed by Thalassospira, Shewanella, Rhodospirillaceae, Gammaprotobacteria, Rhodobacteriaceae and Achromobacter. The microbial community from OBW bioreactor enrichments is intrinsically diverse with clear selection of predominant types and remarkably exhibiting consistent and efficient biodegradation achieved without any nutrient or surfactant addition. Due to there is very little information available in the OBW biodegradation field, this work contributes to the body of knowledge surrounding the treatment improvement of this toxic waste and its potential application in wastewater management.