James Robert is referred to as "Jim-Bob" and, although he tries to shake it off as he gets older, the nickname sticks. In later episodes he wants joins the Air Force as soon as he can and even has his own avaiation helmet. Jim-Bob built a car from scratch, and it runs decently, although it does have occasional problems. He gets in a lot of fights with Ben. In the episode The Home Front he dates adoptive cousin Aimee Godsey.
Jim-Bob is sort of a space cadet, he's always got his head in the clouds dreaming about the future, which sometimes causes him to slack off in his chores. He usually refers to scenarios as being "dumb". Jim-Bob has a fascination with anything mechanical, especially cars, building his own from scratch with assorted scrap metal found in the junkyard. He has a passion for aviation and wants to become an airplane pilot in the Air Force. Like the others, he attends church every Sunday morning with the rest of the family, although he is not really interested in it. He can often be seen sleeping in church, particularly in the episode The Baptism. Jim-Bob appears to get along mostly with his younger sister Elizabeth. He and John-Boy have a fairly good relationship except when John-Boy gets angry at Jim-Bob for running away from him during the episode "the Runaway". In the earlier episodes Jim-Bob discovers he had a twin brother, who died at birth, named Joseph Zebulon Walton.
In the reunion specials of the 90s, Jim Bob has grown incredibly fat.