Bacterial infection is rising as a threatening health issue. Because of the present delay in early diagnosis of bacterial diseases as well as the abuse of antibiotics, it has become a vital issue in the development of in-time detection and therapy of bacterial infections. Herein, we designed a multifunctional nanotheranostics platform based on the unique micro-environment of bacterial infections to achieve specific bioimaging and simultaneous inactivation of the target bacteria. We showed that in bacterial infections, the metal precursors (i.e., HAuCl₄, FeCl₂, and herring sperm DNA) could be readily bio-self-assembled to multifunctional nanoclusters (NCs) that exhibit luminescence, in which AuCl₄^– was biosynthesized via reductive biomolecules such as NADPH to the fluorescent AuNCs. The DNA may assist as an encapsulation and delivery vector, and Fe²⁺ served as a fluorescence intensifier and reduced reactive oxygen species (ROS) to produce the iron oxides. While the bacteria were being visualized, the microenvironment-responsive NCs were enabled to sterilize bacteria efficiently due to electrostatic effect, cell membrane destruction, inhibition of biofilm formation, and ROS accumulation. Besides, the bio-responsive self-assembled NCs complexes contributed to accelerating bacteria-infected wound healing and showed negligible side effects in long-term toxicity tests in vivo. Also, intracellular molecules involved in microenvironmental response were investigated. The work may become an effective strategy for the detection and real-time sterilization of intractable bacterial infections.