Recently,　photothermal　therapy　(PTT)　in　the　second　near-infrared　(NIR-II)　biowindow　has　emerged　as　a　promising　treatment　modality;　however,　its　therapeutic　outcomes　are　still　limited　by　heterogeneous　heat　distribution　and　insufficient　control　of　metastatic　lesions.　Tremendous　efforts　have　been　made　to　overcome　the　PTT＇s　shortcomings　by　combining　PTT　with　immunotherapy,　but　unfortunately　current　strategies　still　suffer　from　low　response　rates,　primary/acquired　resistance　or　severe　immune-related　adverse　events.　Herein,　a　novel　photothermal　agent　and　gene　co-delivery　nanoparticle　(CSP),　with　CuS　inside　the　SiO2　pore　channels　and　PDMAEMA　polycation　on　the　outside　of　SiO2　surface,　is　explored　for　tumor　localized　NIR-II　PTT　and　in　situ　immunotherapy　through　local　generation　of　IL-12　cytokine.　The　resulting　CSP　integrated　with　the　plasmid　encoding　IL-12　gene　(CSP@IL-12)　exhibited　good　gene　transfection　efficiency,　outstanding　NIR-II　PTT　effect　and　excellent　therapeutic　outcomes　both　in　vitro　and　in　vivo.　Meanwhile,　such　an　in　situ　joint　therapy　modality　could　significantly　induce　systemic　immune　responses　including　promoting　DC　maturation,　CD8+　T　cell　proliferation　and　infiltration　to　efficiently　eliminate　possible　metastatic　lesions　through　abscopal　effects.　Hence,　this　creative　combinational　strategy　of　NIR-II　PTT　and　IL-12　cytokine　therapy　might　provide　a　more　efficient,　controllable　and　safer　alternative　strategy　for　future　photo-immunotherapy.　©　2021　The　Royal　Society　of　Chemistry.