Magnesium-ion　batteries　are　promising　candidates　for　the　next-generation　energy　storage　systems.　However,　their　development　is　restricted　by　the　shortage　of　advanced　insertion-type　positive　electrodes.　Hybrid-ion　batteries,　which　combine　the　facile　alkali　metal　ions　extraction/insertion　of　the　cathode　with　the　low-cost　and　high-safety　magnesium　metal　anode,　can　harness　the　individual　benefits　of　both　electrodes　and　achieve　satisfactory　electrochemical　performance.　We　present　a　high-performance　magnesium-potassium　hybrid　ion　battery　utilizing　a　magnesium-potassium　hybrid　ion　electrolyte,　a　magnesium　metal　anode,　and　a　Prussian　blue　analogue　cathode.　The　battery　exhibits　a　discharge　voltage　of　up　to　3.0　V　and　delivers　a　reversible　specific　capacity　of　120　mAh/g,　resulting　in　an　impressive　energy　density　of　360　Wh/kg　(based　on　the　cathode　mass　only).　Moreover,　the　battery　demonstrates　exceptional　cycling　stability,　maintaining　a　capacity　retention　rate　of　96%　after　500　charge-discharge　cycles　at　a　current　density　of　50　mA/g.　The　reaction　mechanism　and　energy　storage　mechanism　of　the　hybrid　ion　battery　were　studied　using　various　electrochemical　testing　methods　and　X-ray　diffraction　analysis.　This　work　may　provide　new　ideas　and　inspire　the　effort　for　the　advancement　of　superior　magnesium　hybrid　ion　batteries.