Yolmo (Hyolmo, Yohlmo) or Helambu Sherpa is a Tibeto-Burman language of the Hyolmo people of Nepal (ISO 639-3: scp, GlottoCode: yolm1234). Yolmo is spoken predominantly in the Helambu and Melamchi valleys in northern Nuwakot District and northwestern Sindhupalchowk District. Dialects are also spoken by smaller populations in Lamjung District and Ilam District and also in Ramecchap District (where it is known as Syuba). It is very similar to Kyirong Tibetan and less similar to Standard Tibetan and Sherpa. There are approximately 10,000 Yolmo speakers, although some dialects have larger populations than others.

Yolmo is both the name of the language (glottonym), and the ethnic group of people who speak the language (ethnonym). Yolmo is also written Hyolmo, Yholmo or Yohlmo. The 'h' in all of these spellings marks that the word has low tone. Sometimes the language is referred to as Yolmo Tam, tam is the Yolmo word for 'language'.

The language is also referred to as Helambu Sherpa. This usage was common in the 1970s (see, for example, Clarke's work from the early 1980s). This name appears to have been an attempt by Yolmo speakers to align themselves with the widely recognised and prosperous Sherpas of the Solu-Khumbu district. While there are many cultural affinities between the two groups, the Sherpa language is not mutually intelligible with Yolmo. With a growing recognition of Nepal's ethnic minorities (Janajati), Yolmo people have moved away from associating themselves with the Sherpas in recent decades.

Yolmo is part of the family of languages called Kyirong-Kagate. The languages of this family are located along the Himalayan hills and mountains mostly on the Nepal side of the border, although Kyirong is in the Tibet Antonymous Region. Along with Yolmo, Kyirong and Syuba, other languages in the family include Tsum, Nubri and Gyalsumdo.

The language family is better considered be Kyirong-Yolmo. Yolmo has far more speakers (at least 10,000) than Kagate (Syuba) (1,500), Yolmo speakers are found in multiple districts, including Melamchi, Lamjung and Ilam, while Kagate speakers are based in Ramechhap. Also, Kagate is an exonym, and speakers now prefer the endonym Syuba, which carries less pejorative stigma than the caste-associated term Kagate ('papermaker').

This is part of a larger cluster of Tibetic languages, which all have their roots in the language that was the basis for Classical Tibetan.

Yolmo speakers traditionally reside in the Helambu and Melamchi Valley regions in the Nuwakot and Sindhupalchowk districts of Nepal. Yolmo speakers migrated to the area, across the Himalaya, from the Kyriong, in what is now Southwest Tibet, over 300 years ago. This migration appears to have occurred slowly over multiple generations, rather than one large migration event. Main villages where Yolmo speakers reside include Melamchi Ghyang, Tarke Ghyang, Nakote, Kangyul, Sermathang, Norbugoun, Timbu, and Kutumsang.

Yolmo speakers are Buddhist, with the role of head Lama patrilineal. Yolmo Lamas are called upon to perform religious rituals for the Tamang-speaking communities that live in villages below the Yolmo-inhabited areas. This has created a strong socio-cultural link between the two groups that is reflected in traditional marriage practice where Tamang women marry into Yolmo villages. There is also a distinct local tradition of pòmbo (often referred to as 'shamanism' in the literature on this topic). The pòmbo tradition, passed from father to son, is focused on healing, particularly with regard to 'soul loss'. This practice appears to be evolving fit with the modern focus on Buddhism among Yolmo people. For example, pòmbo blood sacrifices are no longer performed as commonly. While there are similarities, including a shared etymology, these local practitioners are not formally associated with the Bon of Tibet.