Polyhydroxyalkanoates　(PHAs),　as　biosynthetic　and　biodegradable　polymers,　serve　as　alternatives　to　petroleum-based　plastics,　yet　face　critical　cost　barriers　in　large-scale　production.　While　magnetic　field　(MF)　stimulation　enhances　microbial　activity,　the　optimal　MF　parameters　and　metabolic　mechanisms　for　PHA　biosynthesis　remain　unexplored.　This　study　optimized　magnetic　field　parameters　to　increase　PHA　biosynthesis　in　Haloferax　mediterranei.　A　custom-engineered　electromagnetic　system　identified　110　mT　of　static　magnetic　field　(SMF)　as　the　optimal　level　for　biosynthesis,　reaching　77.97　mg/(Lh)　PHA　volumetric　productivity.　A　pulsed　magnetic　field　caused　oxidative　stress　and　impaired　substrate　uptake　despite　increasing　PHA　synthesis.　Prolonged　SMF　exposure　(72　h)　maximized　PHA　productivity,　while　48　h　of　exposure　attained　90%　efficiency.　Metabolomics　revealed　that　SMF-driven　carbon　flux　redirection　via　regulated　butanoate　metabolism　led　to　a　2.10-fold　increase　in　(R)-3-hydroxybutanoyl-CoA),　while　downregulating　acetoacetate　(0.51-fold)　and　suppressing　PHA　degradation　(0.15-fold).　This　study　pioneers　the　first　application　of　metabolomics　in　archaea　to　decode　SMF-induced　metabolic　rewiring　in　Haloferax　mediterranei.　Our　findings　establish　SMF　as　a　scalable　bioenhancement　tool,　offering　sustainable　solutions　for　the　circular　bioeconomy.