Squat lobsters constitute an exceptional group to address evolutionary studies in marine species because of their high diversity at multiple taxonomic levels. The families included within Galatheoidea are characterized by morphological, molecular, and ecological differences. Previous phylogenetic reconstructions have considered either Galatheidae, Porcellanidae, or even Munidopsidae as the most derived family within Galatheoidea, but evolutionary relationships within the superfamily have not been fully resolved yet. In order to test previous phylogenetic hypotheses on the relative placement of Porcellanidae within the Galatheoidea, and further characterize mitochondrial gene order in Munidopsidae, the first complete mitochondrial genomic sequence of a Galatheidae squat lobster (Galathea aegyptiaca) and the partial mitogenome of Munidopsis polymorpha are reported here. These new sequences complement previous studies to include all extant families and provide further evidence on the importance of mitochondrial gene rearrangements in Galatheoidea. Implications of the new data on the evolution of carcinization within Anomura are also discussed.