The Easternmost Arunachal Himalaya has a complex geological and tectonic setting due to triple junction of Indian Plate, Eurasian Plate and Myanmar Platelet. In this region, high degree of crustal shortening is observed, Tethyan Himalaya part is missing and Siwaliks has been eroded completely. Here, we present an updated geological map of the Easternmost Arunachal Himalaya and a balanced palinspastic cross section through the Himalayan thrust-fold belt, along Roing–Hunli–Anini section. The crustal shortening in this area has been accommodated in the present geologic setting by northward thrusting of litho-units consequently developing a duplex below Hunli Village. Balanced palinspastic cross sections reveal that about 16.2 km thick roof over Hunli window has been eroded implying extreme exhumation, erosion and fast un-roofing processes that landscaped a window at Hunli and a klippe at Mayodia. In comparison with other parts of Himalaya, crustal shortening in the Easternmost Arunachal is maximum with a shortening strain of 83.28% which may be related with the bending around the Eastern Himalayan Syntaxis. It has been observed that crustal shortening in the Lesser Himalaya Sequence in the area is around 81.46%.