Twelve new species of the genus Dichomeris Hübner, 1818 and one new species of the genus Helcystogramma Zeller, 1877 of the subfamily Dichomeridinae of Gelechiidae are described from Vietnam, in combination with Chinese specimens. The new species are D. fascialobella Park & Li, sp. nov., D. flavimaculata Park & Li, sp. nov., D. infundibularis Park & Li, sp. nov., D. lancea Park & Li, sp. nov., D. longivalvata Park & Li, sp. nov., D. marginalis Park & Li, sp. nov., D. myriaodontosa Park & Li, sp. nov., D. ochriella Park & Li, sp. nov., D. quadratella Park & Li, sp. nov., D. sclerospinula Park & Li, sp. nov., D. spinosella Park & Li, sp. nov., D. unilobata Park & Li, sp. nov., and Helcystogramma albimacularis Park & Li, sp. nov. In addition, eighteen Dichomeris species and three Helcystogramma species are reported for the first time from Vietnam, and of these, four previously unknown female are firstly found and described: Dichomeris parvisexafurca Li, Zhen & Kendrick, 2010, Dichomeris argentenigera Li, Zhen & Kendrick, 2010, Dichomeris splendiptera Li & Park, 2017 and Dichomeris parallelosa Park & Ponomarenko, 1998. Images of adults and genitalia for the new species and newly reported species including the firstly described females are provided.