Near-infrared-II (NIR-II) cancer photothermal therapy (PTT) has become more and more attractive as the NIR-II light shows a higher tissue penetrating depth, which leads to better anti-cancer effects. Recently, the members of the MXene family have been reported as NIR-II photothermal agents, possessing a high specific surface area and a fascinating light-to-heat conversion rate at the same time. Herein, we reported a combination of NIR-II photothermal therapy and immune therapy based on the MXene family member niobium carbide (NbC). First, NbC nanosheets (NSs) under 50 nm were prepared. They showed a high photothermal conversion efficiency under a 1064-nm laser, and the NIR-II light showed a deeper tissue penetration depth. Then, a nanoplatform with high R837 stability and a high loading rate was obtained after modification with a polydopamine (PDA) layer on the surface of NbC. With the R837 modification, the percentage of mature dendritic cells (DCs) increased and the immune response enhanced, compared with the immune response caused by PTT only. Finally, a red blood cell (RBC) membrane was applied as a coat over the nanoplatform in order to avoid excessive blood clearance. During experiments, blood circulation of NbC@PDA-R837@RBC nanoparticles (NPs) was prolonged, and all primary tumors were eliminated. Secondary tumors were also inhibited effectively due to the strengthened immune response, proving that NbC@PDA-R837@RBC NPs could inhibit tumor recurrence. All the results above indicated NbC@PDA-R837@RBC NPs as a potential RBC camouflaged nanoplatform for the combination of effective PTT and immune therapy towards tumor treatment.