A series of Eu(2+), Mn(2+) and Tb(3+) singly and co-doped Na2.5Y0.5Mg7(PO4)6 phosphors have been prepared by the solid-state reaction method. X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) have been used to characterise the crystal structure, morphology and composition of the as-prepared samples. The emission intensities of Mn(2+) and Tb(3+) are enhanced due to an efficient energy transfer from Eu(2+) to Mn(2+) and Tb(3+) in Na2.5Y0.5Mg7(PO4)6. In addition, the energy transfer mechanisms between Mn(2+), Tb(3+) and Eu(2+) have been demonstrated. Similarly, white light emission in the Na2.5Y0.5Mg7(PO4)6 host can be realized by adjusting the co-doped concentration of Eu(2+), Tb(3+) and Mn(2+). The results indicate that the as-prepared phosphors have a great prospect as phosphor-converted materials for light-emitting diodes.