Jesse Donald Knotts was born in Morgantown, West Virginia, the youngest of four sons born to farmer William Jesse Knotts and his wife, Elsie Luzetta Knotts (nee Moore). His parents were married in Spraggs, Pennsylvania. His English paternal ancestors immigrated to America in the 17th century, originally settling in Queen Anne's County, Maryland. Knotts' brothers were named Willis, William, and Ralph.

Before he entered high school, Knotts began performing as a ventriloquist and comedian at various church and school functions. After high school, he traveled to New York City to try to make his way as a comedian, but returned home to attend West Virginia University when his career failed to take off. After his college freshman year, Knotts joined the United States Army and spent most of his service entertaining troops. He toured the Pacific Islands as a comedian as part of a G.I. variety show called Stars and Gripes. His ventriloquist act included a dummy named Danny "Hooch" Matador. In a TV Guide interview in the 1970s, he said that he had grown tired of playing straight man for a hunk of wood when he was in the Army. According to Knotts, he tossed the dummy overboard off a ship in the South Pacific. He swore that he could hear the dummy calling for help as the ship sailed on, leaving him bobbing helplessly in the waves. Knotts served in the United States Army from June 21, 1943 to January 6, 1946. Discharged in the rank of Technician Grade 5, which was the equivalent of a Corporal. During his military service, Knotts was awarded the World War II Victory Medal, Philippine Liberation Medal, Asiatic-Pacific Campaign Medal (with 4 bronze service stars), Army Good Conduct Medal, Marksman Badge (with a Carbine BAR) and Honorable Service Lapel Pin. Knotts returned to West Virginia University after being demobilized and graduated in 1948. He married and moved back to New York, where connections he had made while in the Special Services Branch helped him break into show business. In addition to doing stand-up comedy at clubs, he appeared on the radio, eventually playing the wisecracking, know-it-all character "Windy Wales" on a radio western called "Bobby Benson and the B-Bar-B Riders". Knotts got his first major break on television in the soap opera Search for Tomorrow where he appeared from 1953 to 1955. He came to fame in 1956 on Steve Allen's variety show, as part of Allen's repertory company, most notably in Allen's mock "Man in the Street" interviews, always as an extremely nervous man. He remained with the Allen program through the 1959-1960 season. From October 20, 1955 through September 14, 1957, Knotts appeared in the Broadway version of No Time for Sergeants, in which he played two roles, listed on the playbill as a Corporal Manual Dexterity and a Preacher. In 1958, Knotts appeared for the first time on film with Andy Griffith in the film version of No Time for Sergeants. In that film, Knotts reprises his Broadway role and plays a high-strung Air Force test administrator whose routine is disrupted by the hijinks of a provincial new recruit.

What did he say about this
He swore that he could hear the dummy calling for help as the ship sailed on, leaving him bobbing helplessly in the waves.