The emergence of antibiotic resistance in clinically significant pathogens, coupled with their ability to form persistent biofilms, presents a severe challenge in the management of burns and wound infections. To help mitigate the overuse of antibiotics and reduce the prevalence of antimicrobial-resistant bacteria, we have developed a modular theranostic system by blending two types of biocompatible copolymer building blocks, a chromogenic and an antimicrobial component, respectively. For this purpose, a parent active ester copolymer, poly[(hydroxy ethyl acrylamide)-co-(4-benzophenone acrylamide)-co-(pentafluorophenyl acrylate)-co- (ECOSURF EH-3 acrylate)] was synthesized via free radical polymerization. Two different chromogenic building blocks for bacterial enzyme detection were obtained from the parent polymer by functionalization of the pentafluorophenyl acrylate units with enzyme-labile chromogenic compounds, either 5-bromo-4-chloro-3-indolyl β-d-glucuronide (X-GLUC) or 4-nitrophenyl-β-d-glucuronide (PNPG). The antimicrobial building block for infection prevention and treatment was prepared from the parent active ester polymer by modification with antimicrobial peptide SAAP-148. The chromogenic-antimicrobial polymer blend responded to the bacterial enzyme β-glucuronidase with the release of chromophores that produce a visible colour change, enabling rapid, equipment-free proof-of-concept chromogenic detection of Escherichia coli, a major cause of healthcare-associated infections. This polymer blend also demonstrated potent antimicrobial activity against E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii, including multidrug-resistant strains.