Samuel George Ellsworth was born on June 19, 1916 in Safford, Arizona to James Clarence and Julia Claridge Ellsworth. As a child, Ellsworth grew up living in a number of different places including Arizona, Utah, California, and Missouri. He graduated from high school in Kansas City, Missouri in 1934 and attended Kansas City Junior College between 1934 and 1936 studying pre-architecture.

Ellsworth served an LDS mission to the North Central State Mission (headquarters in Minneapolis, Minnesota) between 1936 and 1938. As a missionary, he served as the mission supervisor of Sunday Schools and Mutual and as the mission secretary. During this time, Ellsworth's interests in history replaced his previous ambitions in architecture. Ellsworth returned home to his family in Logan, Utah after his mission. In Logan he attended Utah State Agricultural College and graduated with a bachelor of science degree in history and mathematics in June 1941. After graduation, Ellsworth moved to Bunkerville, Nevada to become principal of the Virgin Valley LDS Seminary and a teacher at Virgin Valley High School from September 1941 to November 1942.

On July 4, 1942, S. George Ellsworth met Maria Smith, daughter of Asahel H. Smith and Pauline Udall Smith of Snowflake, Arizona. George and Maria Ellsworth were married in the Mesa, Arizona LDS Temple on October 24, 1942. Shortly after he married, Ellsworth enlisted in the United States Army Air Force. During the Second World War, Ellsworth served as a staff sergeant, clerk, and administrative inspector at Hammer Field in Fresno, California. From January 1945 to June 1946, Ellsworth served as a chaplain in the Philippines.

After leaving the Army, George Ellsworth continued his education. Between 1946 and 1951, Ellsworth attended the University of California at Berkley. He received his master of arts degree in history in 1947 after finishing his thesis entitled, "A History of Mormon Missionary Activity in the United States and Canada, 1830-1845." Four years later, he received his doctor of philosophy degree in history and philosophy. His completed dissertation was named, "A History of Mormon Missions in the United States and Canada, 1830-1860." During his time in graduate school, Ellsworth was a teaching assistant in History at the University of California, School of Agriculture at Davis, for the 1948-1949 school year. He also served as a teaching assistant at Berkley in 1949 and 1950. During the summer session of 1949 Ellsworth worked as a visiting instructor in history at Utah State Agricultural College in Logan, Utah.

After receiving his PhD at Berkley, Ellsworth returned to Logan and taught history at USAC for the next thirty-one years. He began in January 1951 as an assistant professor of history. In July 1954 he became an associate professor, and in March 1963 he was promoted to full professor. From 1966 to 1969, Ellsworth served as the head of the Department of History. His teaching at USAC included classes in Western Civilization, Greek History, Roman History, History of Utah, Social History of the United States, American Philosophy, Recent United States History, Hispanic American History, Colonial Latin America, Sources and Literature, Introduction to Historical Research, Historical Method and Research, and Ancient World Civilization. During his career, Ellsworth served as a visiting professor at West Virginia University in Morgantown, West Virginia in 1954 and Brigham Young University in Provo, Utah in 1956. In 1983 Samuel George Ellsworth retired and became a professor emeritus.

In addition to his long teaching career at Utah State Agricultural College (in 1957 the college changed its name to Utah State University), George Ellsworth was also a member of many local, state, and national historical associations. Some of these associations included the American Historical Association; the Organization of American Historians; the Western History Association; the Mormon History Association; the Oral History Association; Utah State Historical Society; Cache Valley Historical Society; Utah Academy of Sciences, Arts and Letters; Phi Alpha Theta; Phi Kappa Phi; the Heritage Committee of the Utah American Revolution Bicentennial Commission; and the Utah Endowment for the Humanities. Ellsworth served two terms as president of the Cache Valley Historical Society between 1954 and 1956. He was a member of the executive council in the Utah Academy of Sciences, Arts and Letters. He was the president of the Faculty Association at Utah State University during the 1962-1963 school year. He was the co-founder of the Western Historical Quarterly (the journal of the Western History Association) with Leonard Arrington and became the managing editor of the journal from 1969 to 1979. Ellsworth also served as a member of the board of directors for the American Issues Forum and a member of the executive committee for the Utah Endowment for the Humanities.

George Ellsworth received a number of prominent awards during his career in history. In 1959, George Ellsworth was the Faculty Honor Lecturer of the Utah State University Faculty Association. His lecture, "Zion in Paradise: Early Mormons in the South Seas," was published that same year (Logan, Utah: The Faculty Association, Utah State University, 1959). Ellsworth received the Professor of the Year, Utah State University, Robins Award, in 1965. He was awarded the Mormon History Association Book of the Year Award for Utah's Heritage in April 1973. He became a Fellow in the Utah State Historical Society of September 1973. In 1974 Ellsworth was given the Award of Merit by the American Association for State and Local History. He was awarded an Honorary Life Membership in the Western History Association in 1984. In 1990 George Ellsworth received the Distinguished Service Award from Utah State University.

During his career, Ellsworth wrote numerous articles, reviews, and encyclopedia entries dealing with LDS and Utah history. In 1972, Ellsworth's textbook Utah's Heritage, a history textbook devoted to Utah history, was published. This textbook became the primary text for seventh-grade study of the geography, history, people, and culture of Utah in classrooms across the state. A second edition of the text was published in 1985. Ellsworth also published Dear Ellen: Two Mormon Women and Their Letters in 1974. This book examined the letters of two LDS women. The first was the first wife of a very prominent Latter-day Saint leader and polygamist, while the second was the wife of an LDS pioneer who did not practice polygamy.

After thirty-one years as a professor at Utah State University, Ellsworth retired in 1983 and began to research and write full-time. He conducted the research for four major projects in the lives of his own ancestors. The first of these projects looked at the LDS pioneer outposts of Mount Carmel and Orderville in Utah. Ellsworth's grandfather, Samuel Claridge, had been a leader in the United Order at these settlements. His subsequent book, Samuel Claridge: Pioneering the Outposts of Zion (1987), traces the life of his grandfather.

After his research on Samuel Claridge, Ellsworth began to collect the papers of two of Maria's ancestors, both of whom were important figures in Mormon missionary history. In 1990, The Journals of Addison Pratt was published. This project was an effort to edit and publish the journals of Addison Pratt, an early Mormon missionary to the Society Islands in the South Pacific. Addison Pratt was the great- great-grandfather of Maria Smith. The History of Louisa Barnes Pratt, was published the year after Ellsworth's death in 1997. In this book, Ellsworth once again edited the journals of a family member. Louisa Barnes Pratt was the wife of Addison Pratt and worked with her husband in the Society Islands. She is considered to be the first female Latter-day Saint missionary.

Seasons of Faith and Courage: The Church of Jesus Christ of Latter-Day Saints in French Polynesia a Sesquicentennial History, 1843-1993 was a joint project with Kathleen C. Perrin and was published in 1994. This book discusses the history of the LDS congregations in French Polynesia. Kathleen C. Perrin served with her husband over the Tahiti Papeete Mission from 1989 to 1992 and has a bachelor's degree in French and the humanities from Brigham Young University.

In addition to his distinguished career as a historian, George Ellsworth played an active role in his callings in the Church of Jesus Christ of Latter-day Saints and in his own family. George and Maria Ellsworth have two sons, Stephen George and Mark Addison, and three grandchildren. Samuel George Ellsworth passed away in his home in Logan, Utah on December 22, 1997.