This paper is the second in a series designed to cover taxonomically all Australian species of Diomus Mulsant. Nomenclatural history, diagnoses, digital illustrations and distribution maps are provided for each species. Thirty species are treated in this paper, among those 14 are new: D. bunya sp. nov., D. carbine sp. nov., D. circus sp. nov., D. gingera sp. nov., D. gilvus sp. nov., D. hebes sp. nov., D. kioloa sp. nov., D. leai sp. nov., D. lord sp. nov., D. micrus sp. nov., D. pisinus sp. nov., D. prodigialis sp. nov., D. tasmanicus sp. nov. and D. villus sp. nov. Diomus hypocrtus Weise, 1923 is synonymised with Scymnus mareebensis Blackburn, 1895 syn. nov. Lectotypes are designated for the following taxa to stabilize their taxonomic positions: Diomus hypocrtus Weise, 1923; Scymnus cowleyi Blackburn, 1895; S. elutus Lea, 1902; S. flavifrons var. norfolcensis Lea, 1929; S. frater Lea, 1902; S. impictus Blackburn, 1895; S. inaffectatus Blackburn, 1892; S. insidiosus Blackburn, 1889; S. macrops Lea, 1929; S. maestus Lea, 1926; S. mareebensis Blackburn, 1895; S. obumbratus Blackburn, 1895; S. sublatus Blackburn, 1892; S. triangularis Lea, 1902; S. whittonensis Blackburn, 1892; S. victoriensis Blackburn, 1892 and S. yarrensis Blackburn, 1895.