The Forrest's pika occurs in the eastern Himalayas and Kangri Garpo mountains in southwestern China (northwestern Yunnan and southeastern Tibet), Bhutan, northeastern India (Arunachal Pradesh and Sikkim), and northwestern Myanmar. It is observed in the high elevation regions of northern Arunachal Pradesh, above from sea level in the Tawang district, and also in high elevation regions of the West Kameng and East Kameng districts. In 1997, it occurrence was reported just north of the Upper Dibang Valley district, in Medog County, Tibet. It does not occur in present-day Assam, which belonged to the former Undivided Assam before 1972.