Landon was born Eugene Maurice Orowitz in Forest Hills, New York. His father, Eli Maurice Orowitz, was a Jewish garment manufacturer, and his mother, Peggy O'Neill, was a Catholic actress and dancer. Landon had four siblings: David, Robert, Tom, and Cheryl.
Landon began acting at the age of 14, appearing in several Broadway productions. He signed with Warner Bros. in 1956 and made his film debut in the movie _God Is My Partner_ (1957). He then went on to star in a number of other films, including _Marjorie Morningstar_ (1958), _The Legend of Tom Dooley_ (1959), and _The Longest Day_ (1962).
In 1959, Landon was cast as Little Joe Cartwright on the NBC Western television series _Bonanza_. The show was a huge hit and ran for 14 seasons, making Landon a household name. After _Bonanza_ ended in 1973, Landon went on to star in several made-for-TV movies and television series, including _The Little House on the Prairie_ (1974–1983), _Highway to Heaven_ (1984–1989), and _Us_ (1991).
Landon was also a successful director and producer. He directed a number of episodes of _Bonanza_ and _Little House on the Prairie_, and he also directed several made-for-TV movies. He also produced several television series, including _The Love Boat_ (1977–1987), _Highway to Heaven_, and _Us_.
Landon died of pancreatic cancer on July 1, 1991, at the age of 54. He is survived by his wife, Cindy Landon, and nine children: Mark, Josh, Jason, Michael, Shawna, Christopher, Cheryl, Erin, and Kelly.