The family Trigonalyidae Cresson, 1887, is a small group of parasitic wasps (Hymenoptera: Apocrita) comprising around 150 species worldwide. Among them, the genus Taeniogonalos Schulz, 1906 is the richest in species and the most widely distributed. Four species, namely T. fasciata, T. mongolica, T. subtruncata and T. tricolor, were recorded from the Korean Peninsula. The genus is studied here on the basis of a larger collection of material from South Korea. Six species of Taeniogonalos are recognized, including three species that are newly recorded: T. formosana, T. sauteri and T. taihorina. The published record of T. mongolica in Korea currently seems groundless, and this species should be excluded from the Korean fauna. A key to species identification is provided, with illustrations and description of each species. The hitherto unknown male of T. sauteri is described. We also present new biological data on T. sauteri and T. formosana, including the record of a new family of Diptera as secondary hosts for the family.