Father Shawn Aaron was born in Ridgecrest, California, on January 25, 1968. He is the eldest of four children, with three younger sisters. On April 29, 1978, his family converted to the Catholic Church. They later moved to Modesto, California, where he attended Central Catholic High School, where he earned honors in several sports: football, basketball, baseball, and track and field.

After finishing high school, Father Shawn attended Modesto Junior College, where he studied liberal arts and athletics. In 1989-90, he served as team leader for National Evangelization Teams (NET) and traveled throughout the United States offering retreats for students. After NET, he began working with St. Paul’s Outreach (SPO) in St. Paul, Minnesota, whose mission is to build transformative communities that form lifelong missionary disciples.

In 1991, he joined the Legionaries of Christ in Cheshire, Connecticut. He studied at the Pontifical Athenaeum Regina Apostolorum in Rome, Italy, and earned degrees in Philosophy (1996) and Theology (2002). On Christmas Eve 2002, Father Shawn was ordained a priest at the Legionaries of Christ International College in Rome, Italy.

Following his ordination, he served as director of development for the Legionaries of Christ for several years. From 2007 to 2009, he also served as retreat director for the Our Lady of St. Clare Retreat Center in Cupertino, California.

From 2009 to 2010, he was appointed president of Southern Catholic College in Dawsonville, Georgia. From 2010 to 2017, he was national chaplain of the Lumen Institute, based in Manhattan. He serves on the Board of Directors of Divine Mercy University and the Lumen Institute. He was appointed Territorial Vicar General of North America for the Legionaries of Christ in 2017, a position he held until his appointment as Territorial Director of North America on March 30, 2020 (effective April 1, 2020). He was appointed to a second three-year term on March 21, 2023. His second term began on July 1, 2023.