Peter Simon Deyneka Jr. was born in Chicago on September 13, 1931. He was the second child of Peter and Vera (Demidovich) Deyneka, both of whom had immigrated to the United States from what was then Russian territory. The Deynekas already had one daughter, Ruth, and later had a third child, Lydia. When Peter Jr. was three, his father, who had been an evangelist in the Midwest and a missionary and relief worker in eastern Europe, founded the Russian Gospel Association (later the Slavic Gospel Association), which he headed for the next four decades. The purpose of the organization was to preach the Gospel to Russian (later Slavic) speaking peoples. Peter Jr. from the age of five often traveled with his father as he visited churches to preach and raise support for the Association. At about the age of eight, Peter Jr. committed his life to Christ.

The Deyneka family lived amidst the Russian speaking immigrant community in Chicago. Peter Jr. attended Carl Schurz High School. In high school he was active in the band, where he played the trombone, and the Crusaders Club, a Christian fellowship group, serving as president of the club in his junior year. After graduating from Schurz in 1949 he enrolled as a student at Wheaton College (whose president, V. Raymond Edman, was an old friend of the family). He received his BA in 1953 and then went on to attend Northern Baptist Seminary, from which he received his Master of Divinity degree in 1957. He had already during the time he had been enrolled at Northern Baptist spent one year in Alaska as a SGA worker, serving as a village pastor and evangelist among the Aleut peoples. After graduation he returned to Alaska as a missionary. In 1961 he moved to South America, where he served as director of SGA's Russian Bible Institute in Buenos Aires, Argentina, and taught there for two years and preached in Slavic ethnic colonies throughout South America. Then he moved to Ecuador, where he taped Russian language broadcasts for missionary radio station HCJB in Quito. Radio was again a major part of his next assignment. From 1963-65, after a brief return to the United States, he was loaned to the Evangelical Alliance Mission (TEAM) to work at their station HLKX in Inchon, South Korea. There he was once again involved in developing Russian language evangelistic broadcasts, this time to be broadcast to non-Christian audiences in the Soviet Union. While in Korea, he also worked in his spare time as a civilian military chaplain on United States military bases, assisted young people's groups and preached in local churches.

When he returned to the United States, his next assignment was at SGA's headquarters (now moved to Wheaton) where he became assistant director in 1966. Shortly after his return home, on June 14, 1968, he married Anita Marson. For the next nine years he aided his father, taking over a larger and larger share of the administrative work. Finally in 1975 he became general director upon his father's retirement. (Peter Sr. died in 1987). Peter Jr. continued as head of SGA until 1991. Then his disagreement with the board of the Association over the best way to take advantage over the many new opportunities for building and strengthening the church in Russia due to the collapse of the Soviet Union caused him to resign from SGA and form, together with his wife, a new organization called Peter Deyneka USSR Ministries (later changed to Peter Deyneka Russian Ministries). Through this organization Deyneka planned to serve as a liasion and expeditor between Western evangelistic organizations interested in working in Russia and churches and parachurch organizations in the fomer Soviet Union.

Besides his work for SGA over the years, Deyneka was involved in many other Evangelical ministries. He was a guest lecturer at Fuller Seminary and the Wheaton College Graduate School, a member of the board of directors of the Interdenominational Foreign Mission Association South American Crusades, Society for the Study of Communism and Religion, and the Roumanian Missionary Society. He also co-wrote with Norman Rohrer a biography of his father called Peter Dynamite (1975) and with his wife Anita Christians in the Shadow of the Kremlin (1974) and A Song in Siberia (1977).

Peter Deyneka, Jr. died on December 23, 2000.