Recently, heteroatom-doped three-dimensional (3D) nanostructured carbon materials have attracted immense interest because of their great potential in various applications. Hence, it is highly desirable to exploit a simple, renewable, scalable, multifunctional, and general strategy to engineer 3D heteroatom-doped carbon nanomaterials. Herein, a simple, eco-friendly, general, and effective way to fabricate 3D heteroatom-doped carbon nanofiber networks on a large scale is reported. Using this method,3D P-doped, N, P-co-doped, and B, P-co-doped carbon nanofiber networks are successfully fabricated by the pyrolysis of bacterial cellulose immersed in H3PO4, NH4H2PO4, and H3BO3/H3PO4 aqueous solution, respectively. Moreover, the as-prepared N, P-co-doped carbon nanofibers exhibit good supercapacitive performance.