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The development of high-performance carbonaceous microwave absorbers to achieve full X band (8.2–12.4 GHz) efficient microwave absorption with lower filler loading ratio is highly desirable but remains challenging. Here, a kind of hollow graphene nano-spheres uniformly confined in porous amorphous carbon particles (HGS@PAC) are fabricated via a facile pyrolysis of bi-metal organic framework (bi-MOF). The successful construction of hollow graphene nano-spheres (HGS) by the in situ catalysis of Co in the framework of bi-MOF significantly improve the interface polarization and conductive loss of HGS@PAC, which ensures the high enough absorption intensity with lower filler loading ratio when used as microwave absorbers. The optimal HGS@PAC demonstrate excellent microwave absorption performance, achieving an effective absorption bandwidth of 4.2 GHz which covers the whole X band with 10 …