This inquiry explored Korean mothers’ socioemotional supports and literate mediation strategies for 84 4- and 5-year-old children as they wrote unfamiliar words, and the relation of these strategies and comments to Korean children's Hangul reading. The mother–child writing interactions were videotaped. Eight strategies of maternal literate mediation were thereafter distinguished and five socioemotional comments were coded. Mothers of 5-year-olds employed a coda-centered (i.e., emphasis on the final consonant of a syllable) strategy more often than those of 4-year-olds. The maternal coda focus was uniquely associated with children's word reading over and above mothers’ education and children's age, grade, vocabulary, and writing skill. Maternal literate mediation centered on the consonant–vowel (CV) subsyllabic unit, which clarified children's reading of CV Gulja (Korean written syllable). These results propose that efficient maternal literate mediation strategies center on salient psycholinguistic grain size of Korean language such as CV (body) and coda subsyllabic units. In addition, the two socioemotional categories of process and critical comments were uniquely associated with children's reading. Findings emphasize the importance of Korean language and culture in mothers’ early scaffolding to ease children's literacy acquisition.