Extended-spectrum β-lactamases (ESBLs) are a major contributor to antimicrobial resistance in Gram-negative bacteria, posing a significant global public health challenge. Among these, the Guiana extended-spectrum β-lactamase (GES) family has emerged as an important but relatively underrecognized group of class A ESBLs. Initially identified in Klebsiella pneumoniae from French Guiana, GES-type enzymes have since been reported worldwide in various bacterial species, particularly Pseudomonas aeruginosa and Acinetobacter baumannii. GES enzymes exhibit considerable heterogeneity, with certain variants demonstrating the ability to hydrolyze carbapenems, thereby complicating treatment options. The global dissemination of ESBLs, including GES types, is largely driven by mobile genetic elements such as plasmids and integrons, as well as the spread of high-risk clones like Escherichia coli ST131. Detection of GES-type ESBLs remains challenging due to variability in phenotypic expression and limitations of routine diagnostic methods. Although standardized screening and confirmatory tests are recommended, molecular techniques such as PCR and sequencing provide more reliable identification. This review highlights the epidemiology, molecular characteristics, detection challenges, and clinical significance of GES-type ESBLs. Understanding their evolution and dissemination is essential for improving surveillance, guiding appropriate antimicrobial therapy, and developing effective infection control strategies.