This research paper presents a comprehensive comparative study of idioms expressing temporal meaning in Russian and English. The main objective of the study is to analyze semantic, structural, and cultural features of time-related phraseological units and to examine their role in reflecting national worldview and mentality. In Russian, time is perceived as a continuous natural flow, closely connected to seasonal cycles, cultural traditions, and emotional experiences: ―day after day,‖ ―in the twinkling of an eye,‖ ―once in a hundred years.‖ These idioms illustrate duration, speed, rarity of events, and the philosophical approach to life, emphasizing patience, observation, and subjective perception. In English, time-related idioms highlight a rational and pragmatic understanding of time: ―time flies,‖ ―once in a blue moon,‖ ―in the nick of time.‖ Time is seen as a resource that should be managed, planned, and used efficiently. The methodology includes comparative-analytical, contextual, and componential analysis, which allows identifying semantic nuances, stylistic features, cultural connotations, and usage patterns of idioms. The findings show that idioms not only serve linguistic purposes but also reflect cultural values, traditions, and national perceptions of time. Comparative analysis reveals both universal patterns and language-specific differences, helping to understand temporal concepts in cross-cultural contexts. The practical significance of the study lies in its application for foreign language teaching, translation, and development of intercultural competence. In conclusion, temporal idioms function as more than linguistic expressions; they act as carriers of cultural memory and national worldview, providing insight into how different societies conceptualize and value time.