One-dimensional　(1D)　N-doped　carbon　nanofibers　decorated　with　ultrafine　(∼4.5　nm)　SnFe2O4　nanoparticles　(denoted　as　SFO/N-CNFs)　are　successfully　synthesized　by　a　combination　of　electrospinning　and　solvothermal　process,　and　their　microwave　absorption　(MA)　properties　are　reported　for　the　first　time.　With　only　5　wt%　filler　loading　in　a　silicone　rubber　matrix,　the　optimum　reflection　loss　(RL)　could　reach　−46.5　dB　and　the　qualified　frequency　bandwidth　(RL　＜　−10　dB)　can　be　capable　of　4.8　GHz　at　1.6　mm,　exhibiting　better　comprehensive　absorption　performance　relative　to　other　analogous　absorbers.　The　lightweight　and　highly　efficient　MA　of　SFO/N-CNFs　is　largely　ascribed　to　the　improved　impedance　matching　and　satisfactory　attenuation　ability　caused　by　the　synergistic　effect　between　the　ultrasmall-sized　SFO　nanoparticles　(NPs)　and　1D　N-CNF　matrix.　This　work　not　only　offers　a　novel　and　promising　high-performance　microwave　absorber,　but　also　offers　a　general　approach　to　designing　and　fabricating　ultrasmall　transition　metal　oxide　nanoparticle　decorated　carbon-based　composite　nanostructures　for　multifunctional　applications.　©　2023　The　Royal　Society　of　Chemistry.