Born in Toronto, Donaldson first joined the CBC in 1967 as an editor with National Radio News. During her time with CBC Radio, she served as Senior Editor of The World at Six, Sunday Morning Magazine and various news specials. She reported from Viet Nam during the war, and later produced Michael Maclear's Vietnam: The Ten Thousand Day War, a series of documentary films on the conflict. In 1971, Donaldson went to CBC Winnipeg as the producer of the popular early evening news show 24 Hours.
Two years later, she returned to the network in Toronto as a producer on Newsmagazine and news specials.
After a five-year stint as a field producer on CTV's W5, Donaldson joined Ryerson Polytechnical Institute in 1975 as an instructor in Broadcast Journalism, in addition to teaching at the University of Western Ontario in the Journalism Program for Native People.
During the 1980s, she was married to Arthur Gelgoot (d. 2004), an accountant. The couple divorced.
Donaldson returned to the CBC in 1985 as Co-ordinator of Regional Programming, TV News and Current Affairs. She was appointed head of CBC Newsworld during its inception stages in 1987 and oversaw the launch of the new specialty service in 1989.