<p>Shiga toxin-producing <i>E. coli</i> (STEC) strains are particularly concerning due to their zoonotic potential and environmental persistence. Ruminants, especially sheep and cattle, serve as primary reservoirs, often shedding pathogenic strains asymptomatically and contributing to foodborne outbreaks through contamination of animal-derived products. This study aimed to characterize antimicrobial-resistant <i>E. coli</i> strains isolated from dairy sheep in Brazil, focusing on phylogenetic backgrounds, resistance profiles, and genomic features. From 65 rectal swab samples collected across five herds in two Brazilian states, 65 <i>E. coli</i> isolates were recovered. Of these, 27.7% showed antimicrobial resistance to at least one drug tested, and 32.3% were identified as STEC. Resistance was most frequently observed against sulfamethoxazole-trimethoprim, tetracycline, and gentamicin. Notably, one isolate (LZB-RS-110) exhibited an extended-spectrum β-lactamase (ESBL) phenotype and a multidrug-resistant profile. Whole-genome sequencing identified clinically relevant resistance genes (e.g., <i>bla</i>_CTX-M-8, <i>tetB</i>, <i>sul2</i>), virulence genes (<i>stx1</i>, <i>stx2</i>), and metal tolerance operons. The <i>bla</i>_CTX-M-8 gene, harbored on a predicted conjugative IncI1 plasmid, was flanked by mobile genetic elements, suggesting a high potential for horizontal gene transfer. Phylogenomic analysis revealed that LZB-RS-110 is closely related to international isolates from wild and domestic animals, highlighting the global dissemination of high-risk <i>E. coli</i> lineages. These findings underscore the critical role of sheep in the ecology of zoonotic and resistant <i>E. coli</i>, and the broader implications for food safety and One Health. Enhanced surveillance and rational antimicrobial use in livestock are urgently needed to mitigate the spread of resistance and safeguard public health.</p>