Chitin is the second most abundant natural polysaccharide after cellulose. But degradation of chitin has never been reported in haloarchaea. In this study, we revealed that Haloferax mediterranei, a metabolically versatile haloarchaeon, could utilize colloidal or powdered chitin for growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) accumulation, and the gene cluster (HFX_5025-5039) for the chitin catabolism pathway was experimentally identified. First, reverse transcription polymerase chain reaction results showed that the expression of the genes encoding the four putative chitinases (ChiA(Hme), ChiB(Hme), ChiC(Hme), and ChiD(Hme), HFX_5036-5039), the LmbE-like deacetylase (Dac(Hme), HFX_5027), and the glycosidase (GlyA(Hme), HFX_5029) was induced by colloidal or powdered chitin, and chiA (Hme), chiB (Hme), and chiC (Hme) were cotranscribed. Knockout of chiABC (Hme) or chiD (Hme) had a significant effect on cell growth and PHBV production when chitin was used as the sole carbon source, and the chiABCD (Hme) knockout mutant lost the capability to utilize chitin. Knockout of dac (Hme) or glyA (Hme) also decreased PHBV accumulation on chitin. These results suggested that ChiABCD(Hme), Dac(Hme), and GlyA(Hme) were indeed involved in chitin degradation in H. mediterranei. Additionally, the chitinase assay showed that each chitinase possessed hydrolytic activity toward colloidal or powdered chitin, and the major product of colloidal chitin hydrolysis by ChiABCD(Hme) was diacetylchitobiose, which was likely further degraded to monosaccharides by Dac(Hme), GlyA(Hme), and other related enzymes for both cell growth and PHBV biosynthesis. Taken together, this study revealed the genes and enzymes involved in chitin catabolism in haloarchaea for the first time and indicated the potential of H. mediterranei as a whole-cell biocatalyst in chitin bioconversion.