The article is devoted to the functioning and transformation of phraseological units in theVietnamese mass media. The study material was the media texts of Vietnamese periodicals, mainly electronic, such as the newspapers NhHn dHn, TuÜi trÂ, QuHn Eài nhHn dHn, TiÈn phong, Lao Eàng,NOng nghiÎp and several others for the period 2010-2020. It is noted that phraseological units are one of themost important semantic and expressive means used in media texts. Phraseological units are used in both traditional (basic) and transformed forms. Especially often, phraseological units are used in the headings and subheadings of media texts to attract the attention of readers, enhance expressive coloring and expressiveness, create an ironic effect and engage readers in a language game. The following main types of transformationare considered: formal (structural), semantic, and combined structural-semantic. The types of structural transformation are distinguished: replacing lexical components, expanding the composition of thephraseological unit, breaking the phraseological unit, reducing the component composition. The semantictransformation consists in the literalization of the meanings of the components of the phraseological unit, which in this case is perceived simultaneously in both the literal and figurative sense. In the combined (formal-semantic) transformations, several varieties of modifications are used simultaneously. The necessityof distinguishing between occasional (contextual) transformations and normal variants of phraseological units is indicated. The use in the language of the media of a significant number of new phraseological units not yetrecorded in phraseological dictionaries is noted, examples of such units are given.