The haloarchaeon Haloferax mediterranei synthesises poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) under unfavourable nutritional conditions without the addition of any precursor to the culture, which is an advantage compared to other microbial counterparts able to synthesise polyhydroxyalkanoates (PHA). PHBV is a biodegradable polymer showing physiochemical properties of biotechnological and biomedical interest and can be used as an alternative to plastics made from chemical synthesis (which are not environmentally friendly). The versatile metabolism of H. mediterranei makes possible the use of wastes as a carbon source for cellular growth and PHA synthesis. In this work, cellular growth and the production and characterization of PHBV using two different confectionery wastes have been analysed and compared with cellular growth and PHBV synthesis in a standard culture media with glucose of analytical grade as a carbon source. PHBV granules produced have been analysed by TEM and the biopolymer has been isolated and characterised by GC-MS, FTIR NMR, and DSC. Results reveal that H. mediterranei can use these two residues (R1 and R2) for pure PHBV production, achieving 0.256 and 0.983 g PHBV/L respectively, which are among the highest yields so far described using for the first-time wastes from the candy industry. Thus, a circular economy-based process has been designed to optimize the upscaling of PHBV production using haloarchaea as cell factories and valorising confectionery wastes.