Born in Oregon City, Oregon, Latourette was educated at McMinnville (later Linfield) College (B.S., 1904) and Yale University (B.A., 1906, M.A, 1907, Ph.D. 1909), then spent a year as traveling secretary for the Student Volunteer Movement, before going to China in 1910 on the teaching staff of Yale-in-China at Changsha in Hunan province. He returned home in ill health after two years. Following two years of recovery in Oregon, Laourette taught part time at Reed College in Portland until he joined the faculty of Denison University in Granville, Ohio, in 1916. While at Denison his first major book, The Development of China, appeared (1917), he wrote The Development of Japan (1918; later reissued as The History of Japan), and he began working on A History of Christian Missions in China (1929). In 1918 he was ordained to the Baptist ministry. In 1921 he was appointed (as successor to Harlan Page Beach) the D. Willis James Professor of Missions at Yale University Divinity School; in 1949 he was named Sterling Professor of Missions and Oriental History at Yale, his post until he retired in 1953.
In 1945 his presidential address to the American Society of Church History was titled "A Historian Looks Ahead: The Future of Christianity in the Light of Its Past"; his presidential address to the American Historical Association in 1948 was "The Christian Understanding of History." He also served as president of the American Baptist Convention, the Japan International Christian University Foundation, and the Far Eastern Association (later the Association for Asian Studies). Unmarried, Latourette lived on the campus at Yale Divinity School where was affectionately known as "Uncle Ken" especially by his student secretaries and those who joined his weekly discussion groups for prayer and Bible study. An evangelical, he regularly taught a Sunday morning class for students at a local Baptist church. In 1952 he was serving on thirty boards and committees in New Haven, and New York. He received honorary doctorates from seventeen universities in five countries.
Latourette's career at Yale was marked by a steady stream of publications that established his international reputation as historian and apologist of Christian missions. Most notable were two monumental series, A History of the Expansion of Christianity (7 vols., 1937-1945) and Christianity in a Revolutionary Age: A History of Christianity in the Nineteenth and Twentieth Centuries (5 vols., 1958-1962). His central thesis was that "throughout its history [Christianity] has gone forward by major pulsations. Each advance has carried it further than the one before. Of the alternating recessions, each has been briefer and less marked than the one which preceded it" (History of the Expansion, vol.7 , p. 494). He believed that "in A.D. 1944 Christianity was affecting more deeply more different nations and cultures than ever before." Yet at the time of his death he was unsure whether the period from 1914 to 1960 was a period of advance or retreat. Latourette was killed when an automobile accidentally hit him in front of his family home in Oregon City.