We report the 5.101-Mbp high-quality draft assembly of the Escherichia coli strain ATCC 23506 (serovar O10:K5:H4, also known as NCDC Bi 8337-41) genome. This uropathogenic strain, commonly referred to as E. coli K5, produces N-acetyl heparosan, a glycosaminoglycan-like capsular polysaccharide and precursor to the anticoagulant pharmaceutical heparin. Metabolic reconstruction of this genome will enable the prediction of gene deletions and overexpressions that lead to increased heparosan production.