The Sikkimese Bhutia language (Tibetan: འབྲས་ལྗོངས་སྐད་, Wylie: 'bras ljongs skad, THL: dren jong ké, Tibetan pronunciation: [ɖɛ̀n dʑòŋ ké]; 'rice valley language') is a Sino-Tibetan language spoken by the Bhutia people of the indian state of Sikkim and parts of Koshi province in eastern Nepal, and Bhutan. It is one of the official languages of Sikkim.

The Bhutia refer to their own language as Drendzongké (also spelled Drenjongké, Dranjoke, Denjongka, Denzongpeke or Denzongke) and their homeland as Drendzong (Tibetan: འབྲས་ལྗོངས་, Wylie: 'bras-ljongs, 'Rice Valley'). Up until 1975, Sikkimese was not a written language. After gaining Indian statehood, the language was introduced as a school subject in Sikkim and the written language was developed.

Sikkimese is written using Sambhota script and Zhang Yeshe De Script, which it inherited from Classical Tibetan. Sikkimese phonology and lexicon differ markedly from Classical Tibetan, however. SIL International thus describes the Sikkimese writing system as "Bodhi style". According to SIL, 68% of Bhutia were literate in the Tibetan script in 2001.

Sikkimese belongs to the Sino-Tibetan language family, and more specifically, is classified as a Tibetic language, descending from Old Tibetan. For most of the language's existence Sikkimese was an oral language, and it was not until 1975 when Sikkim became a part of India that a written language was developed. Until this point, Classical Tibetan was the primary mode for writing. After Indian statehood, Sikkimese was one of the many minority languages in the region to be taught in schools over the next few years. As a result of this, a written language was developed, adopting a modified version of the Tibetan script. The first literary materials were school books translated from Tibetan, and in the following years original works would be authored, including novels, poetry, and plays. While the total number of bhutia authors number approximately 30, the language continues to be used in different media. As of 2021, currently one active newspaper exists, with another paper that has plans to begin printing again. Moreover, in the last 2 decades multiple dictionaries have been published. Finally, the "Bhutia Language Website Development Committee" plans to launch an informational website about the language and peoples in the future.

Speakers of Sikkimese can understand some Dzongkha, with a lexical similarity of 65% between the two languages. By comparison, Standard Tibetan, however, is only 42% lexically similar. Sikkimese has also been influenced to some degree by the neighbouring Yolmowa and Tamang languages.

Due to more than a century of close contact with speakers of Nepali and Tibetan proper, many Sikkimese speakers also use these languages in daily life.

Dialects are for the most part quite mutually intelligible in Sikkimese as most differences that exist are minor. One big difference, however, is the lack of honorifics in some Northern villages, discussed in more detail in a separate section below. Also occurring in these villages are the largest dialectal differences in pronunciation and vocabulary. In the area of Bhutan closest to Sikkim, Sikkimese speakers can understand Northern varieties of Sikkimese much more easily than they can varieties from West Sikkim. It is a local belief that the people in these Northern villages originated from this same area in Bhutan.

Sikkimese a total of eight vowels and 43 consonants in its inventory. Words in Sikkimese split into high or low registers all based on voice quality and pitch. The register of Sikkimese words can be predicted most of the time based on their starting phoneme but nasals and liquids are unpredictable. Due to the unpredictability of some of Sikkimese registers and the lack of difference between modal and breathy voicing, Sikkimese is considered a toned language even though tone itself is not provide too much of a functional load like other languages that are also considered to be toned.