The Arma custos is an important natural enemy of agricultural and forest pests. The complete mitochondrial genome (mitogenome) of A. custos was determined in the present paper. This mitogenome is 15,629 bp in size and comprises of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. All protein-coding genes are initiate with ATN, except ND2, COX1, ATP8 and ND1 use TTA or TTG as the start codon, and terminate with TAA with the exception of COX2 and ND5 which use a single T residue as the stop codon. All tRNAs, ranging from 63 to 72 bp, have the cloverleaf structure except tRNASer(AGN). The monophyly of the subfamily Asopinae is highly supported by the phylogenetic tree and A. custos is recovered as sister to the remaining Asopinae species.