Background <p>Wastewater monitoring is an effective approach for assessing public health, providing insight into circulating pathogens and their associated antimicrobial resistance genes. <i>Klebsiella pneumoniae</i>, a clinically and environmentally significant opportunistic pathogen, was investigated in this study.</p> Methods <p>120 wastewater samples were collected from various sources, and the isolates were analyzed for antimicrobial susceptibility using the Kirby–Bauer disk diffusion method against 11 antibiotics, in addition to PCR-based detection of β-lactamase and virulence genes.</p> Results <p>Among 81 <i>K. pneumoniae</i> isolates from different wastewater sources, 51% were resistant to at least one antibiotic, with hospital wastewater being the main source of resistant strains (74.2%), followed by community wastewater (50%), WWTP influent (35%), and effluent (21.4%). Resistance was most frequent to ampicillin/sulbactam (35.8%), whereas gentamicin showed the highest efficacy (4.9%). Multidrug resistance was observed in 53.7% of resistant isolates, primarily in samples from hospitals (69.6%) and WWTP influents (57.1%). ESBL producers accounted for 67.5% of isolates, while 32.5% co-produced ESBLs and carbapenemases. The <i>bla</i>_<i>SHV</i> gene was detected in all isolates (100%), while <i>bla</i>_{<i>OXA−48</i>} (22.5%) was the most common carbapenemase gene. Almost all isolates (98.8%) possessed at least one virulence gene, with <i>mrkD</i> (96.3%) and <i>entB</i> (79.0%) being the most detected. Additionally, 86.5% of the isolates carried two or more virulence genes. Notably, no hypervirulent strains were observed.</p> Conclusion <p>Overall, wastewater from diverse sources constitutes a significant reservoir of multidrug-resistant and virulent <i>K. pneumoniae</i> strains. Their environmental release poses a considerable public health risk, highlighting the urgent need for improved wastewater management and continuous microbial surveillance.</p>