She celebrated her birthday yesterday with more than 70 family and friends.
Religious Superior Sr Bridget Donnelly said Sr Marie assisted hospital residents at mealtimes, and sometimes set the staff members' dining table for meals.
Sr Marie, who was imprisoned by the Nazis in France in World War 2, gave a speech in which she said she had led a ''fortunate life''.
The Little Sisters of the Poor order that gave her 81 years of ''companionship'' ensured she was never alone, she said.
Speaking to the Otago Daily Times, she said she had ''no idea'' why she had kept such remarkably good health, but believed ''God is very good to me''.
Asked about her assistance to other residents, she said helping at mealtimes was not ''too strenuous''.
Community living was ideal for the elderly, as it prevented loneliness, she said.
She greatly enjoyed her party, and said she had another planned with younger members of her extended family.
Pope Francis had issued a certificate of celebration, and she received ''the usual'' recognition from the Queen.
A delegation of seven nuns from Australian and New Zealand centres, led by the Sydney-based Sister Provincial, Sr Ann Kilmartin, attended the birthday celebration.
Sr Ann said while it was becoming less remarkable to live to 100, Sr Marie was exceptional for her vitality.
Born Anne Fitzpatrick and brought up in Arrowtown, Sr Marie left home in 1933 to move to Dunedin to enter religious life.
She travelled to China with the order in 1936, where she was posted to Shanghai to serve in a rest-home, which was besieged by the invading Japanese army, following a civil war that broke out soon after she arrived.
In 1940, she was sent to occupied France, where she was declared a spy by the Germans and imprisoned for weeks.
After the war, she served various overseas postings, before returning to Dunedin first in 1962 and then, following other postings, permanently in 1975.
Retired Catholic Bishop of Dunedin Len Boyle led a Mass to mark the occasion.
Sr Marie was ''extraordinary'' for her age, he said.
