New-typed magnetic and color-tunable bifunctional Janus nanofibers have been successfully fabricated by electrospinning technology using a specially designed parallel spinneret. The Janus nanofiber consists of two strands of nanofibers assembled side-by-side, one strand nanofiber has tuned magnetism and the other one possesses color-tunable photoluminescence. The Janus nanofibers possess superior magnetic and luminescent properties due to their special nanostructure. Tunable colors from bluish green to orange can be realized in the flexible Janus nanofibers by varying the content of Eu(BA)(3)phen complex, and furthermore, white-light-emitting flexible Janus nanofibers are achieved using rare-earth complexes as luminescent centers. In particular, it is the first time to report the influence of Fe3O4 nanoparticles on the fluorescent color of the magnetic-fluorescent nanomaterials. The synthesized products have potential applications in color displays, nano-bio-label materials, and anti-counterfeit materials.