During her career she worked on the designs of many important buildings in Canada and the United States, including the Robson Square and the Law Courts Complex in Vancouver, the National Gallery of Canada, the Canadian Chancery in Washington D.C., the Library Square at the Vancouver Public Library, the Museum of Anthropology at the University of British Columbia, and Northwest Territories Legislative Assembly Building in Yellowknife. Cornelia Oberlander died of COVID-19 in Vancouver, British Columbia on 22 May 2021 during the COVID-19 pandemic in British Columbia. She died one month before her one hundredth birthday.