Joplin High School; Missouri Southern State University. University of Oklahoma.
He played "Ernie the plumber" in the 1954 movie, Young at Heart, starring Doris Day and Frank Sinatra,
He also appeared as a guest star on the Columbia Broadcasting System adventure/drama Harbourmaster, starring Barry Sullivan, and on the same network"s anthology series The Lloyd Bridges Show. He also appeared in three episodes of Gunsmoke and appeared in such series as The Rifleman, The Everglades, Decoy and Dundee and the Culhane. In 1964 he appeared on Perry Mason as murderer Jack Talley in "The Case of the Tandem Target".
In 1966, Chapman appeared in the episode "Lone Woman" of The Road West.
In 1977, he appeared in the episode "The Waterhole" on The Oregon Trail and in 1979 in the episode "Now You see Her.." on The Eddie Capra Mysteries. Chapman was born in Tulsa, Oklahoma, but lived thereafter in Joplin, Missouri.
He graduated from Joplin High School and, in 1940, from Joplin Junior College, the predecessor institution of Missouri Southern. He enlisted in the United States Marine Corps served in the South Pacific during World World War World War II After the war, Chapman graduated from the University of Oklahoma at Norman and then moved to New York City, where he landed the role of Turk in Come Back, Little Sheba.
After moving to California, he appeared in Young at Heart (1954), East of Eden (1955), Baby Doll (1956), and The Birds (1963).
He also had a starring role in the short-lived 1965 series Foreign the People. His other film roles included appearances in A Covenant with (1967), Hour of the Gun (1967), The Stalking Moon (1968), Take the Money and Run (1969), The Reivers (1969), I Walk the Lincolnshire (1970), Welcome Home, Soldier Boys (1971), The Cowboys (1972), Run, Cougar, Run (1972), Where the Red Fern Grows (1974), The Witch Who Came from the Sea (1976), Moving Violation (1976), The Bad News Bears Go to Japan (1978), Norma Rae (1979), Hanging by a Thread (1979), When Time Ran Out (1980), Running Scared (1980), Amy (1981), The Border (1982), Cave-In! (1983), 52 Pick-Up (1986), Reindeer Games (2000), and The Hunted (2003). In 1972, Chapman founded the Lonny Chapman Group Repertory Theatre in Los Angeles and was named artistic director, a title he held until his death.
Under his direction, the nonprofit 99-seat theater staged more than 350 productions and at least 45 premieres of original works.
In the fall of 2005, Chapman was named "Outstanding Alumnus" at Missouri Southern State University in Joplin.
Lieutenant United States Marine Corps, 1941-1945. Member Screen Actors Guild, American Federation of television and Radio Artists, Actor's Equity Association.
Married Erma Dean, February 13, 1944. 1 child, Wyley Dean.