Prosthetic joint infection (PJI) is a major complication of total joint arthroplasty (TJA) with inadequate treatment options. This investigation seeks to evaluate the efficacy of a novel treatment for PJI, the combination of D-amino acids and gold nanorods dispersed in a hydrogel (PhotothermAA gel), that targets the bacterial biofilms responsible for PJI treatment resistance. Using a rabbit hemiarthroplasty model of PJI, we demonstrated that PhotothermAA gel reduces bacterial biofilms on prostheses as quantified using scanning electron microscopy (SEM) with image pixel classification (median biofilm coverage 93.0% (interquartile range [IQR] 73.7% to 98.7%) in infected sham group; 97.0% (IQR 81.0% to 99.5%) in infected irrigation and debridement [I&D] group; 44.8% (IQR 29.4% to 54.0%) in infected I&D + antibiotics group; 37.3% (IQR 26.3% to 47.5%) in infected PhotothermAA + antibiotics group; p<0.001). Further, we demonstrated a confocal microscopy staining and imaging protocol that allows us to examine bacterial viability and biofilm protein and polysaccharide content before and after PhotothermAA gel treatment. Future work may be conducted to enhance the understanding of the efficacy and mechanism of PhotothermAA gel in order to better determine its translational potential.