We designed an injectable hydrogel by dissolving MoS/BiS-PEG (MBP), doxorubicin (DOX) and agar into water for the concurrent tumor photothermal and chemotherapy. The formed solution was able to be intra-tumorally (I.T.) administered into tumor at a relatively high temperature and automatically formed a hydrogel after cooling to body temperature. The resultant Agar/MBP/DOX (AMD) hydrogel can act as a macro-vessel to retain the MBP nanosheet and DOX and restrict their access to body fluid circulation. Moreover, AMD hydrogel did not compromise the photoacoustic and computed tomography imaging capacity, as well as the photothermal and chemotherapy efficiency of MBP nanosheets and DOX. The heat from the photothermal transformation of MBP nanosheet can promote the drug-release from the hydrogel and thus enable an on-demand drug release. Furthermore, antibiotics were also able to be encapsulated in the hydrogel to avoid the potential wound infection during tumor surgery.