This study was aimed to (1) describe the high school students’ perceptions towards the use of teacher’s translanguaging in EFL classrooms and (2) identify the aspects to which teacher’s translanguaging can facilitate students in learning English. This study was carried out in the form of qualitative research with a case study approach. This study was conducted at a senior high school in Karanganyar, specifically in the first semester of grade 11. Observation, questionnaire, and interview were used to collect the data. The validity test technique used was methodological triangulation by crosschecking data from the three data collection techniques. Member checking was also used to test the credibility of interview data. The data analysis technique used is the interactive model from Miles, Huberman, and Saldana (2014). The first research finding showed that most students have positive perception towards the use of teacher’s translanguaging in EFL classrooms. The second finding showed that teacher’s translanguaging facilitated students in learning English in the aspects: 1) vocabulary: word meaning and synonyms and antonyms; 2) parts of speech: nouns, verbs, and adjectives; 3) grammar errors in punctuations, prepositions, and conjunctions; and 4) the difference of phonological system of English and Indonesian. Teacher's translanguaging mostly helps in linking students' previous knowledge with the help of native language to understand the target language (English).