The genus Cosmophasis Simon, 1901 is reviewed for Australia and some localities in Papua New Guinea, southeast Asia and the Pacific islands. The study is based on new and type material and includes 24 species, of which 17 are described as new: C. baehrae, C. banika, C. colemani, C. courti, C. darwini, C. harveyi, C. hortoni, C. humphreysi, C. kairiru, C. kohi, C. lungga, C. motmot, C. panjangensis, C. rakata, C. sertungensis, C. tavurvur and C. trobriand. C. micans (L. Koch, 1880) and C. modesta (L. Koch, 1880), described from Australia, have neither been located in the collections nor in field and have not been included here, however, according to their original description, both seem to be valid species. Amycus tristriatus L. Koch, 1880 and Maevia ombria Thorell, 1877 are reinstated as Cosmophasis tristriatus (L. K.) and C. ombria (Th.), respectively. C. marxii (Thorell, 1890) is synonymised with C. ombria (Thorell, 1877) and C. muralis Berry, Beatty & Prószyński, 1997 with C. tristriatus (L. Koch, 1880). For all species complete documentation is given, including diagnoses, the data on intraspecific variation and the maps of actual and predicted distributions. The key for species is not included because the genitalic characters are too complex to describe concisely. Based upon morphological criteria, five species groups are proposed. Remarks on relationships and distribution of Cosmophasis are given.