This study aimed to describe the presence and geographical distribution of Gram-negative bacteria considered critical on the priority list of antibiotic-resistant pathogens published by the World Health Organization, including carbapenem-resistant Enterobacteriaceae, carbapenem-resistant Acinetobacter spp., and carbapenem-resistant Pseudomonas aeruginosa. A systematic review of original studies published in 5 databases between 2010 and 2021 was conducted, including genotypically confirmed carbapenem-resistant isolates obtained from canines, felines, and their settings. Fifty-one articles met the search criteria. Carbapenem-resistant isolates were found in domestic canines and felines, pet food, and on veterinary-medical and household surfaces. The review found that the so-called “big five”—that is, the 5 major carbapenemases identified worldwide in Enterobacterales (New Delhi metallo-β-lactamase, active-on-imipenem, Verona integron-encoded metallo-β-lactamase, Klebsiella pneumoniae carbapenemase, and oxacillin [OXA]-48-like)—and the 3 most important carbapenemases from Acinetobacter spp. (OXA-23-like, OXA-40-like, and OXA-58-like) had been detected in 8 species in the Enterobacteriaceae family and 5 species of glucose non-fermenting bacilli on 5 continents. Two publications used molecular analysis to confirm carbapenem-resistant bacteria transmission between owners and dogs. Isolating critically important human carbapenem-resistant Gram-negative bacteria from domestic canines and felines highlights the importance of including these animal species in surveillance programs and antimicrobial resistance containment plans as part of the One Health approach.