This　Letter　reports　the　synthesis　approach　and　application　of　colloidal　suspensions　containing　gradient　alloy　quantum　dots　(QDs)　and　silica　hybrid　spheres　with　improved　thermal　and　photostability,　invisible　QD　aggregation,　and　high　material　compatibility.　These　hybrid　nanospheres　are　characterized　by　using　silica　spheres　as　cores,　adsorbing　QDs　as　one　shell,　and　then　coating　a　silica　layer　as　another　shell　(termed　SiO2-QD-SiO2).　They　were　synthesized　by　using　Stöber　and　adsorption　methods.　The　experimental　conditions　affecting　the　optical　properties　were　fully　investigated.　A　light-guiding　microstructure　array　(LGMA)　was　fabricated　and　tested　for　photoluminescence　demonstration.　After　accelerated　aging　tests　for　240　h　under　85　°C,　40%　relative　humidity,　and　450　nm　blue　light　excitation,　the　luminance　of　the　SiO2-QD-SiO2　LGMA　remained　stable,　which　was　1.6　times　greater　than　that　of　untreated　QD　samples.　This　structure　with　long-term　photothermal　stability　could　pave　the　way　for　displays　or　lighting　applications.　©　2020　American　Chemical　Society.