It's the first time Pope Francis has visited the country and the first time a pontiff has visited Scandinavia since Pope John Paul II in 1989.
The one-day event with the Lutheran World Federation (LWF) in the southern city of Lund was to commemorate the progress the two churches have made in reconciling since believers began breaking away from the Catholic Church during the Protestant Reformation over theological differences.
It included a special service using a prayer book written by both churches.
Pope Francis quoted Martin Luther and praised him for restoring Scripture to the church.
The pontiff joined Bishop Munib Younan of the Lutheran Church in signing a joint declaration to work together to heal conflicts, take care of the environment and help refugees.
The commemoration marks the beginning of a year's worth of events leading up to the 500th anniversary of the Reformation, often marked on October 31st 1517 when Martin Luther nailed his work, called The Ninety-Five Theses, on the door of All Saints Church in Wittenberg in Germany.
His work outlined his theological opposition to some Catholic teachings of the day, and many churches still believe the doctrines today.
Since the Reformation the Catholic and Lutheran Churches have agreed on major theological issues, including justification, outlined in several landmark documents.
LWF General Secretary Rev Dr Martin Junge told Vatican Radio: "The LWF is approaching the Reformation anniversary in a spirit of ecumenical accountability.
"I'm carried by the profound conviction that by working towards reconciliation between Lutherans and Catholics, we are working towards justice, peace and reconciliation in a world torn apart by conflict and violence."
Anders Arborelius OCD, Bishop of the Catholic Church in Sweden, added: "The ecumenical situation in our part of the world is unique and interesting.
"I hope that this meeting will help us look to the future so that we can be witnesses of Jesus Christ and His gospel in our secularized world."