Injectable pH and thermo-responsive hydrogel incorporated with photothermal agent and method of preparation thereof for controlled on-demand drug release The  present invention provides a method for synthesis of an in-situ injectable pH and thermo-responsive hydrogel and photothermally activated (external stimuli) drug  release. The injectable pH and thermo-responsive hydrogel comprising of Pluronic F127 and PAA based hydrogel incorporated with surface modified gold nanorods (as  photothermal agent) and an anti-cancer drug. Therapeutic drugs for diseases other than cancer can also be incorporated. For the gelation of the injectable hydrogel,  cross-linker along with polymerization initiator and catalyst are also incorporated. The invention is advantageous because it provides a localized drug availability &  thus treatment due to its relative ease of preparation, low cost, in situ gelation characteristics, and controlled on demand drug release up on external stimuli. Method for  the hydrogel synthesis (within short gelation duration) and irradiation parameters for drug release are disclosed for the use of synthesized hydrogel as photo- chemotherapeutic platform for cancer & allied treatments. In addition to this, the effect of external stimuli (near infrared irradiation) as well as internal stimuli (tumor  pH) on the drug release through synthesized injectable hydrogel is also described.