This study investigated the occurrence and genetic features of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli recovered from dumpsite leachates in Abakpa Nike, Enugu State, where rapid urban expansion and poor waste handling contribute to environmental contamination. The work was motivated by the growing burden of antimicrobial resistance and the role of polluted environments as reservoirs of resistant organisms. Leachate samples were collected from six municipal dumpsites over six weeks and analyzed using standard microbiological procedures, including cultural examination, biochemical testing, and 16S rRNA gene sequencing for confirmation of isolates. Mean heterotrophic E. coli counts ranged from 0.9 ± 2.0 × 10³ to 1.4 ± 10.0 × 10³ cfu/ml, with the highest values observed at site C and lower counts at sites D, E, and F. Antibiotic susceptibility profiling revealed widespread resistance, with all isolates exhibiting resistance to ciprofloxacin, gentamicin, and meropenem, whereas resistance to nitrofurantoin was lowest at 33.3%. The calculated multiple antibiotic resistance (MAR) indices indicated exposure to high-risk contamination sources. Polymerase chain reaction (PCR) analysis showed that all isolates carried BlaTEM and BlaCTX-M genes, confirming the molecular basis of ESBL production. Strong biofilm formation was also detected among the isolates, implying an enhanced ability to persist in adverse environmental conditions and withstand antimicrobial pressure. Overall, the findings demonstrate that dumpsite leachates in the study area serve as significant reservoirs of multidrug-resistant E. coli, underscoring the need for improved waste management and continuous monitoring to mitigate public health risks.