Repeated expeditions conducted in Arunachal Pradesh resulted in the discovery of a unique Begonia, Begonia bijantiae D.Borah, Taram & M.Hughes, belonging to Begonia sect. Diploclinium. This species is described here based on collections made in Hunli, Lower Dibang Valley District of Arunachal Pradesh. Additionally, a poorly known species, Begonia ovatifolia is illustrated with first‐ever published photographs, accompanied by an expanded description based on a collection from West Kameng district of the state.