Different institutions recognized that antimicrobial resistance is a global health threat that has compounded by the reduction in the discovery and development of new antimicrobial agents. Therefore, the development of new antimicrobial therapeutic strategies requires immediate attention to avoid the 10 million deaths predicted to occur by 2050 as a result of multidrug-resistant (MDR) bacteria. Despite the great interest in the development of repurposing drugs, only few repurposing drugs are under clinical development against Gram-negative critical-priority pathogens. In this chapter, we aim: (i) to discuss the therapeutic potential of the repurposing drugs for treating MDR bacterial infections, (ii) to summarize their mechanism of action, and (iii) to provide an overview for their preclinical and clinical development against these critical-priority pathogens.