We report the synthesis of a novel kind of non-rare earth (RE) red-emitting phosphor via incorporation of rhodamine (RhB) into porous boron nitride (BN) microfibers to form RhB@BN composite. The RhB@BN composite with typical one-dimensional (1D) fibrous morphology exhibits intense visible red-light emission, which can be attributed to the reduced dye aggregation via the confinement of RhB within porous BN, as well as the efficient energy transfer from BN host to RhB dyes. Moreover, the quantum efficiency of RhB@BN composite annealed after 150°C treatment is as high as 86.94%. The strong interaction between RhB dyes and BN host plays an important role for maintaining the good thermal stability of the composite. The developed low-cost and environmentally friendly RhB@BN composite is envisaged to be highly valuable red-emitting phosphor.