In 1980, she was ordained in the Church of Sweden and held positions in parish ministry until 1996. She earned her Ph.D. (Dr. Theol.) from Lund University, Sweden, in 1999.

From 1999 to 2001, she was regional director for Europe of the Science and Religion Course Program of the Center for Theology and the Natural Sciences, Berkeley, California, USA. Between 2001-2007, Jackelén taught systematic theology and religion and science at the Lutheran School of Theology at Chicago and was director of the Zygon Center for Religion and Science. From 2007-2014, she was Bishop in Lund diocese, Church of Sweden.

A founding member of the International Society for Religion and Science (ISSR), she has served on the board of directors of the Metanexus Institute on Religion and Science and the board of the European Society for the Study of Science and Theology (ESSSAT).  She also serves on the editorial advisory board of the journal Theology and Science and the editorial council of Dialog, A Journal of Theology.

Her publications include books in German, English, and Swedish as well as numerous articles in theology and religion and science, published in various languages. In 2004, she published The Dialogue between Religion and Science: Challenges and Future Directions. An English translation of Time and Eternity: The Concept of Time in Church, Science, and Theology (published in German 2002) came in 2005. In 2011, she published Gud är större (God is greater, Arcus).

In June 2017, Jackelén was awarded The Lambeth Cross for Ecumenism by the Archbishop of Canterbury “For her services to ecumenism – especially her leadership in addressing human, theological and social issues in partnership and dialogue.”