In 1934, Sumrall began traveling abroad. He preached in Tahiti and New Zealand and established a church in Brisbane, Australia. He traveled with Howard Carter throughout eastern Asia and Europe. In South America, Sumrall met Louise Layman. The couple were married on September 30, 1944, and had three children: Frank Lester (born 1946), Phillip Stephen (1950) and Peter Andrew (1953-2015). The Sumrall and his family spent many years in the Philippines during the 1950s. The culmination of his evangelistic work in that country was the establishment of the Cathedral of Praise in Manila. With over 24,000 members, it is the largest congregation in the Philippines.
In 1957, Sumrall established the Lester Sumrall Evangelistic Association. He would also found World Harvest Bible College (now Indiana Christian University) and World Harvest Magazine. In 1963, Sumrall moved to South Bend, Indiana, to pastor Christian Center Cathedral of Praise (now Christian Center Church). It was around this time that he withdrew from the Assemblies of God denomination.
In 1968, Sumrall began what would become World Harvest Radio International. Sumrall has been called the "father of Christian television". From 1972 to 1997, he acquired television stations throughout the United States as part of World Harvest Television (also known as LeSEA Broadcasting). In 1987, Sumrall established a humanitarian aid organization, LeSEA Global Feed the Hungry.
Sumrall wrote many works during his lifetime ranging from topics such as evangelism, miraculous healing, demons and exorcism, angels and more. Some of his works were of a more polemic nature warning about such things as the dangers and detrimental effects of such things as movies and Roman Catholicism. He also wrote at least one autobiography "Adventuring with Christ".