UNIS endorses a model of enriched language education in which all students acquire proficiency in two languages in addition to English and their home language(s). UNIS aims to provide authentic language learning experiences that have age appropriate global significance and that give students the opportunity to explore the similarities shared by people of the diverse cultures of the United Nations International School community.

UNIS offers language instruction in nine modern languages: Arabic, Chinese, English, French, German, Italian, Japanese, Russian and Spanish. Students take French or Spanish from Pre-K to Grade 10 as their second language. From Grade 7 to 10, students add an additional language, different to the one they are taking as their second language, to be chosen among Arabic, Chinese, French, German, Italian, Japanese, Russian or Spanish. Each language is offered in different levels of proficiency according to the nomenclature of the Common European Framework and ranging from Pre-A1.1 to B2.2. 

At the IB level, in Grades 11 and 12, UNIS offers Language A, Language B and Ab Initio courses for the eight languages plus a number of others as self-study.