The South Australian Glossy Black-Cockatoo Calyptorhynchus lathami halmaturinus is extinct on mainland Australia, and occurs only on Kangaroo Island. Between 1995 and 2016, a successful long-term Recovery Program more than doubled the population of this taxon on Kangaroo Island. This paper documents the first records of nesting by Glossy Black- Cockatoos on the Dudley Peninsula on eastern Kangaroo Island in 2015 and 2018, at a time when flock size had increased to 35 individuals in post-breeding counts on the Dudley Peninsula. Nesting there is evidence of the growth and expansion of the Glossy Black-Cockatoo population over the past 25 years, which is likely a result of conservation efforts. This new eastern nesting site expands the breeding range of this subspecies 13 km east, and to the part of Kangaroo Island that is closest to mainland South Australia.