Whole-genome sequencing of 24 Proteus mirabilis isolates revealed the clonal expansion of two cefoxitin-resistant strains among patients suffering community-onset infection. These strains harboured blaCMY-2 within a chromosomally located integrative and conjugative element (ICE) and exhibited multidrug resistance phenotypes. A predominant strain, identified in 18 patients, also harboured the PGI-1 genomic island and associated resistance genes, accounting for its broader antibiotic resistance profile. The identification of these novel multidrug-resistant strains among community-onset infections suggests that they are endemic to this region and represent emergent P. mirabilis lineages of clinical significance.