We present a nearly complete mitochondrial genome (mitogenome) of Hymenolepis diminuta from a Danish isolate, which was reassembled and comprehensively annotated using whole-genome sequencing data retrieved from the Sequence Read Archive (accession No. ERS056110). Although 2 mitogenomes of H. diminuta have previously been submitted to GenBank (accession No. AP017664, Danish isolate; NC_002767, putative German laboratory strain), the former lacks noncoding regions, while the latter harbors relatively short repeat units. Our newly reconstructed mitogenome is 14,090 bp long, comprising 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a 643-bp noncoding region containing 7 tandem repeat units. The annotated sequence has been deposited in the Third Party Annotation database in GenBank (accession No. BK071817). Phylogenetic analysis based on mitogenomic sequences confirmed a close relationship between H. diminuta and Hymenolepis nana. This improved mitogenome sequence represents a valuable resource for comparative mitogenomic and phylogenetic investigations within the families Hymenolepididae, Taeniidae, and Diphyllobothriidae.