In this study, a new efficient Ce 3+-doped fluorosulfide phosphor, Y 2(Ca,Sr)F 4S 2:Ce 3+, was obtained by using solid-state methods in a sealed silica ampoule. The synthesized Y 2(Ca,Sr)F 4S 2:Ce 3+ was characterized by powder X-ray diffraction and refined with Rietveld methods. Y 2(Ca,Sr)F 4S 2:Ce 3+ can be excited by blue light (440-470 nm) and shows yellow-to-orange broadband emission peaking at 553-590 nm with a quantum efficiency of 16-31%. Non-radiative transitions between Ce 3+ ions in Y 2CaF 4S 2:Ce 3+ and Y 2SrF 4S 2:Ce 3+ hosts have also been demonstrated to be attributable to dipole-dipole interactions, and the critical distances were calculated to be 18.9 and 19.3 Å. The possible mechanism of the tunable luminescence properties was described on the basis of band structure calculations. In addition, a white LED device was fabricated by using Y 2(Ca,Sr)F 4S 2:Ce 3+ phosphor pumped with a 460 nm blue chip. The CRI value and CCT were measured to be 74-85 and 3500-8700 K, respectively, showing promising potential for solid-state lighting.