Mervyn Bennion Arnold was born in Salt Lake City, Utah. He received a bachelor’s degree in business and a master’s degree in public administration from Brigham Young University. He was married to Devonna Kress Arnold in 1971. They are the parents of six children. He founded and co-owned a building and development company. Later he expanded and was a cofounder of Guardian State Bank. He served as a as a General Authority Seventy of The Church of Jesus Christ of Latter-day Saints from April of 2003 to October of 2018. He has also served as Area President of the South America South Area in Buenos Aires, Argentina, as Assistant Executive Director in the Temple and Missionary Departments, as a member of the Boundary and Leadership Change Committee, the President of the Brazil South Area, and as a counselor in the Brazil North and Brazil South Areas. In addition to serving as a full-time missionary in the Northern Mexico Mission, he was president of the Costa Rica San José Mission.