This study focused on isolating and analyzing bacteriophages against multidrug-resistant, ESBL-positive Escherichia coli strains obtained from the One Health Institute of the University of Debrecen. Antimicrobial resistance of the ten strains was assessed using the disc diffusion method, revealing resistance to multiple antibiotics but sensitivity to carbapenems. Bacteriophages were isolated from 15 wastewater samples in Budapest using the spot test, and 127 phage-containing samples were identified. Among these, 23 phage genomes were sequenced using Oxford Nanopore MinION, with 22 being virulent and one temperate. Genome sizes ranged from 37 to 136 kb, with no detected virulence or resistance genes, and 48%–72% of predicted proteins were hypothetical. The phages were genetically diverse, with several classified into known families or genera, and ten were E. coli-specific, making them promising candidates for future phage therapy development.