Mary Ellen Sloan was born in Montana, moved to Salt Lake City as a teenager, graduated from the University of Utah in 1972, and received a Juris Doctor degree from the University of Utah in 1975.

After graduating she worked at South Dakota Legal Services on the Rosebud Sioux Reservation in Mission South Dakota, and Utah Legal Services, before joining the law firm of Larry Echohawk and Bill Thorne, in Salt Lake City, primarily focusing on representing Native American Tribes and individuals. She represented the Paiute Indian Tribe of Utah in its successful effort to gain restoration of its status as a federally recognized tribe, and the Northwestern Band of Shoshone in achieving recognition of its status as a federally recognized tribe.

Her career eventually led her to join the Salt Lake County District Attorney's Office, as a deputy District Attorney, and then to become the Assistant Deputy District Attorney of the Civil Division, the first woman to hold the position of Assistant Deputy.

In 2001 she began studying with Dennis Genpo Merzel Roshi in Salt Lake City, received Jukai (Buddhist precepts) in 2004 and Shukke Tokudo (ordination as a Zen monk) in 2005, Dharma Transmission (Shiho) in 2017, and in 2023 her teacher gave her the final seal of approval (Inka). She is also a certified Big Mind facilitator.

She is an attorney and is the mother of one daughter.