Flexible magnesium (Mg)-air batteries provide an ideal platform for developing efficient energy-storage devices toward wearable electronics and bio-integrated power sources. However, high-capacity bio-adaptable Mg-air batteries still face the challenges in low discharge potential and inefficient oxygen electrodes, with poor kinetics property toward oxygen reduction reaction (ORR). Herein, spinel nickel cobalt oxides (NiCo 2 O 4 ) nanowires immobilized on nitrogen-doped Ti 3 C 2 T x (NiCo 2 O 4 /N-Ti 3 C 2 T x ) are reported via surface chemical-bonded effect as oxygen electrodes, wherein surface-doped pyridinic-N-C and Co-pyridinic-N moieties accounted for efficient ORR owing to increased interlayer spacing and changed surrounding environment around Co metals in NiCo 2 O 4 . Importantly, in polyethylene glycol (PVA)-NaCl neutral gel electrolytes, the NiCo 2 O 4 /N-Ti 3 C 2 T x -assembled quasi-solid wearable Mg-air batteries delivered high open-circuit potential of 1.5 V, good flexibility under various bent angles, high power density of 9.8 mW cm -2 , and stable discharge duration to 12 h without obvious voltage drop at 5 mA cm -2 , which can power a blue flexible light-emitting diode (LED) array and red smart rollable wearable device. The present study stimulates studies to investigate Mg-air batteries involving human-body adaptable neutral electrolytes, which will facilitate the application of Mg-air batteries in portable, flexible, and wearable power sources for electronic devices.