Regulation　of　Eu2+　dopants　in　different　cation　sites　of　solid-state　materials　is　of　great　significance　for　designing　multicolor　phosphors　for　light-emitting　diodes　(LEDs).　Herein,　we　report　the　selective　occupation　of　Eu2+　for　multiple　cationic　sites　in　KSrScSi2O7,　and　the　tunable　photoluminescence　from　blue　to　cyan　is　realized　through　Eu2+　doping　concentration-dependent　crystal-site　engineering.　Eu2+　preferably　occupies　the　K　and　Sr　sites　in　KSrScSi2O7　at　a　low　doping　concentration,　resulting　in　a　440　nm　blue　emission.　As　the　Eu2+　concentration　increases,　a　new　Eu2+　substitution　pathway　is　triggered,　that　is,　Eu2+　enters　the　Sc　site,　leading　to　the　red-shifted　emission　spectra　from　440　to　485　nm.　The　doping　mechanism　and　photoluminescence　properties　are　corroborated　by　structural　analysis,　optical　spectroscopy　study,　and　density　functional　theory　calculations.　The　optical　properties　of　the　as-fabricated　white　LEDs　are　studied,　which　demonstrates　that　these　phosphors　can　be　applied　to　full-spectrum　phosphor-converted　LEDs.　This　study　provides　a　new　design　strategy　to　guide　the　development　of　multicolor　Eu2+-doped　oxide　phosphors　for　lighting　applications.　　©　2021　The　Authors.　Published　by　American　Chemical　Society.