Data were collected from 65 archived Klebsiella pneumoniae isolates retained during the University Hospitals Dorset outbreak investigation. For each isolate, non-identifiable metadata—including collection date, hospital department and specimen source—were collated from outbreak records. Species identity was confirmed by MALDI-TOF MS, and phenotypic antimicrobial susceptibility was determined by Kirby–Bauer disc diffusion against 11 antibiotics using EUCAST breakpoints. Isolates underwent Oxford Nanopore whole-genome sequencing, followed by genome assembly and in-silico identification of sequence type, antimicrobial-resistance genes and plasmid replicons. The resulting isolate metadata, resistance classifications and plasmid-associated resistance genotypes were compiled in Appendix File S1.