For most of his career, DeWitt sang tenor for The Statler Brothers. Songs he wrote for the group include "Flowers on the Wall"—which was a greatest hit during the late 60s and early 70s that made the group popular—"Things," "Since Then," "Thank You World," "The Strand," "The Movies," and "Chet Atkins' Hand." In 1968, while the group was under contract to Columbia Records, DeWitt recorded a solo single composed of the songs "She Went A Little Bit Farther" and "Brown Eyes". In November 1981, DeWitt took a leave of absence from The Statler Brothers due to surgery and treatment for Crohn's disease, from which he had suffered since adolescence. At his suggestion, Jimmy Fortune was tapped as his temporary replacement. He would rejoin the group in June of the following year, but this arrangement lasted less than a week. DeWitt officially retired that same month with Fortune becoming his permanent replacement. Three years later, DeWitt, feeling that his health had gradually improved through continuing treatment, mounted a solo career. During this time, he would return to touring and would release two albums, Here to Stay and On My Own. The latter album gave Dewitt his only solo chart appearance with a cover of "You'll Never Know", which made it to #77. Despite the lack of success he would remain with the Compleat label through 1987. DeWitt was married three times. From 1961 through 1973, he was married to Glenda Kay Simmers, with whom he had two sons and two daughters. He was later married to Joyce Anne Arehart, and then Judy Fitzgerald Wells. DeWitt would remain active as a performer until late 1989, when his health rapidly declined, which culminated in his death on August 15, 1990, in Waynesboro, Virginia. The cause of death was heart and kidney disease, stemming from complications of Crohn's. Lew Dewitt Boulevard in Waynesboro was named in his honor in 1992. In 2011, amateur video of DeWitt performing at the Burley Tobacco Festival in the late 1980s surfaced and was posted onto YouTube. The set is notable for the inclusion of what would become his final single, "Moonset." As of 2020, none of DeWitt's solo recordings have been released in any digital format.
