Gies died Monday after a short illness, according to an announcement on her website. No other details were provided.
The scattered papers Gies gathered up after Anne and her family were taken from their hiding place in Amsterdam to concentration camps were later compiled by Anne's father into one of the most widely read nonfiction books of all time.
According to the Anne Frank Center USA in New York City, "Anne Frank: The Diary of a Young Girl" has been translated into more than 67 languages and tens of millions of copies have sold since its publication in 1947. For millions of young people, Anne's story is their initial exposure to the Holocaust.
The famous words from Anne's closing passage -- "I still believe, in spite of everything, that people are truly good at heart" -- have inspired hope and tolerance for the generations after World War II who have tried to grasp the horror of the annihilation of millions of Jews under Adolf Hitler.
Yet Anne's story might never have surfaced had it not been for Gies, a Christian, who said in her 90s that she felt no fear when she risked her life to protect and bring provisions to the Frank family during the war.
"Real strength is being able to carry on when times are hard," Gies told Oprah magazine in 2002. "I had no time to occupy myself with fear. There was work to be done."
After the war, Gies enjoyed modest fame for her part in keeping Anne Frank and her family alive while they hid from the Nazis and for rescuing Anne's writings in the hope of returning them to Anne after the war.
Anne, almost 16, and her sister Margot, 19, both died of typhus in the Bergen-Belsen concentration camp a few weeks before it was liberated
For the Dutch, Gies, who was the last survivor of the Franks' five most important helpers, "is very much the heroine of the Anne Frank story, since she represents the ideal," according to Carol Ann Lee's 2003 book "The Hidden Life of Otto Frank."
On what would have been Anne Frank's 75th birthday, Gies, then 96, told People magazine: "I have written many things about her. But, after all this time, it is still extremely painful that Anne didn't live -- that none of them did."
Miep Gies -- pronounced "Meep Gees" -- was born Hermine Santrouschitz in Vienna on Feb. 15, 1909, five years before World War I began in Europe. The war caused widespread food shortages and, like many, young Gies became sick from malnutrition.
At 11, Gies was sent to the Netherlands by her parents, who were concerned for her welfare. "I was bundled up in whatever my parents could find and taken to the cavernous Vienna railway station," she said. She recalled thinking, "What have I done to be so ill and abandoned?"
Years later, she realized, it was this thought that surfaced when she saw what was happening to the Jews under Hitler.
Many other sickly children also were waiting with Gies for the train, all with the same cards hung about their necks. Hers had the name of people she had never met, who spoke Dutch, not German. She rarely saw her birth parents after that.
Her new family, who eventually moved from a small town in Holland to the bustling city of Amsterdam, gave her the Dutch nickname Miep.
In 1933, Gies took an office job with Otto Frank, whose firm specialized in pectin and spices. Frank had recently left Germany because of Hitler's anti-Jewish policies, and his family, including his youngest daughter, Anne, were soon to follow.
Over the years, Anne grew to idolize the older and more glamorous Gies, who had blond hair and blue eyes. When Gies married social worker Jan Gies in 1941, she said Anne "treated us almost as though we were two movie stars."