"Today, I pass on this emblematic figure of womanhood and of consecrated life to the whole world of volunteers: may she be your model of holiness!" he said.
"Let us carry her smile in our hearts and give it to those whom we meet along our journey, especially those who suffer. In this way, we will open up opportunities of joy and hope for our many brothers and sisters who are discouraged and who stand in need of understanding and tenderness."
After the Mass, Pope Francis continued immediately with praying the Sunday Angelus, first greeting and thanking everyone who took part, especially the Missionaries of Charity, whom he called the "spiritual family of Mother Teresa."
He also greeted the various national delegations, pilgrims, volunteers and workers of mercy, and anyone who, through media, joined in the celebration from around the world.
"I entrust you to the protection of Mother Teresa: she teaches you to contemplate and adore Jesus Crucified every day, to recognize him and serve him in our brothers in need."
The Pope concluded his Angelus message by asking for prayers especially for Sister Isabel, 51, a Spanish missionary nun who was shot and killed Sept. 2 in Port-au-Prince, Haiti during what appears to have been a robbery.
Pope Francis prayed for an end to violence, and for greater security around the world.
"We also remember other Sisters that recently have experienced violence in other countries," he prayed, doing so "by addressing in prayer the Virgin Mary, Mother and Queen of all saints."
Hannah Brockhaus is Catholic News Agency's senior Rome correspondent. She grew up in Omaha, Nebraska, and has a degree in English from Truman State University in Missouri.