Stable and efficient phosphor systems for white light-emitting diodes (LEDs) are highly important with respect to their application in solid-state lighting beyond the technical limitations of traditional lighting technologies. Therefore, inorganic solid-state conversion phosphors must be precisely selected and evaluated with regard to their special material properties and synergistic optical parameters. In this perspective, we present an overview of the recent developments of LED phosphors; firstly, general photoluminescence-controlling strategies for phosphors to match LED applications have been evaluated; secondly, state-of-the-art and emerging new LED phosphors have been demonstrated. Then, methodologies for the discovery of new LED phosphors by mineral-inspired prototype evolution and new phase construction, as well as combinatorial optimization screening, and the single-particle-diagnosis approach, have been analyzed and exemplified. Finally, future developments of LED phosphors have been proposed.