Developing　single-component　white-light　phosphors　remains　challenging　due　to　the　difficulty　in　achieving　dual　emission　from　mixed-valent　activators.　Herein,　we　present　a　carbon-modulated　reduction　synthesis　(CARS)　method　to　fabricate　Eu2+/Eu3+　co-doped　La3Si2O8Cl　(LSOCl)　phosphors　without　requiring　hazardous　reducing　atmospheres.　By　modulating　carbon　content　(Eu　:　C　=　1　:　0-2.4),　the　Eu2+/Eu3+　ratio　is　effectively　controlled,　enabling　tunable　emission　from　pink　to　white　and　yellow　under　365　nm　UV　excitation.　The　optimized　LSOCl:7%Eu　(Eu　:　C　=　1　:　1.9)　exhibits　broadband　emission　(390-720　nm)　with　a　high　color　rendering　index　(Ra　=　85.05),　cool　white　light　(5489　K,　CIE:　0.33,　0.38),　and　stable　performance　under　varying　currents.　Additionally,　LSOCl:7%Eu　(Eu　:　C　=　1　:　1.4)　shows　excitation-dependent　chromaticity　shifts:　minimal　changes　under　solar-blind　UV　(250-280　nm)　but　dramatic　variations　at　280-350　nm,　facilitating　rapid　detection.　A　solar-blind　UV　detector　was　designed,　demonstrating　fast　response,　high　resolution　(50%　CIE　shift　at　330　nm),　and　anti-interference　capability.　The　CARS　method　offers　an　eco-friendly,　scalable　route　for　dual-emission　phosphors,　showcasing　their　dual　utility　in　high-quality　white　LEDs　and　sensitive　UV　detection　technologies.