Pope Francis canonized Mary Elizabeth Hesselblad at a ceremony in Saint Peter's Square that took place just a few months before he is due to visit Sweden, which is a largely secular country.
She had been beatified by Pope John Paul II in 2000 after a 30-year campaign.
Hesselblad is only the second Swede to receive sainthood, following Saint Bridget 625 years ago.
Sunday's ceremony was attended by Sweden's Culture Minister Alice Bah-Kuhnke and more than 250 Swedish pilgrims.
Hesselblad was born in 1870 into a Lutheran family with 13 children before heading to the United States in her teens in search of better economic opportunities.
She landed in New York and became a nurse. She converted to Catholicism in 1902 and left for Rome two years later.
In Rome, she settled with the Carmelites, where she took the habit of the Bridgetines, an order founded in the 14th century by Saint Bridget, who was canonized in 1391.
Hesselblad restored the order in Rome in 1911 and brought it back to Sweden a decade later, as part of her effort to unite all Christians and breathe new life into an order and a religion that had been languishing after the Reformation.
She is credited with promoting peace between Catholics and non-Catholics, and for pushing other Christians and non-Christians alike toward the Catholic Church.
She reportedly saved more than 60 Jews during World War II, hiding families inside her convent in Rome for about 6 months before the war ended.
Yad Vashem, Israel's Holocaust remembrance center, recognized her actions when it honored her as one of the Righteous Among the Nations in 2004, an award bestowed upon non-Jews who helped Jews during the Holocaust.
Mother Elizabeth died in Rome in 1957 at the age of 87.
Pope Francis is due to visit Sweden – a country with just 150,000 Catholics – from October 31st to November 1st to mark the 500th anniversary of the Lutheran Reformation, which will be celebrated in 2017.
Francis also canonized Polish priest Jan Papczynski, who took on the religious name of Stanislaus of Jesus and Mary, on Sunday.