This research focuses on the analysis of the types and functions of codeswitching in cosmetic product reviews used by X users. This research applied a qualitative method with a content analysis approach. The data were tweets containing code-switching using two languages in cosmetic product reviews, Indonesian and English, which were gathered from #racuninmakeup. They were taken from the 1st – 14th of January 2024 on X. The analysis of the research was based on Poplack’s theory, such as intra-sentential switching, inter-sentential switching, and tag switching. As for the functions of code-switching, was based on Appel and Muysken’s theory, such as referential, expressive, metalinguistic, directive, phatic and poetic. The researcher found that the analysis of makeup product reviews reveals a significant use of code-switching, particularly intrasentential switching, where English terms are integrated into predominantly Indonesian sentences whether in positive or neutral reviews. However, there is no relationship between the types of code-switching and the types of the review, because in some of the data intra-sentential switching types stand alone and are sometimes accompanied by inter-sentential switching and tag switching types. Based on Appel and Muysken’s theory, this linguistic phenomenon serves multiple functions, especially referential functions, and is influenced by the nature of the makeup industry, the target audience, and the expressive needs of the reviewers.