A morphological review of the mantid genus Deroplatys Westwood, 1893 is presented. The type specimens of Deroplatys desiccata Westwood, 1839, D. trigonodera Westwood, 1889 and D. rhombica De Haan, 1842 are illustrated. The holotype of D. angustata Westwood, 1841 has been rediscovered in the NHM collection and the description of the external morphology and male genitalia are provided. Deroplatys horrifica Westwood, 1889 is now a new synonym of D. lobata (Guérin-Méneville, 1838). Three new species namely Deroplatys kinabaluensis sp. nov., Deroplatys nebula sp. nov. and Deroplatys xuzhengfai sp. nov. are described and illustrated. New identification keys were generated for both sexes. The distribution of the genus Deroplatys species is discussed and mapped.