LeBaron was commissioned in the Marine Corps reserves while in college and served as a lieutenant in the Korean War after graduation. He was wounded twice and was decorated with the Purple Heart. For his heroic actions on the front lines, he was awarded the Bronze Star. Due to his diminutive size, 5 feet, 7 inches, and leadership skills from his military service, he was sometimes known as the "Littlest General".
In his seven seasons with the Redskins he started 55 of a possible 72 games at quarterback (he played in 70 of those 72 games). He was also the primary punter for his first three seasons with Washington (he would punt 171 times for a total of 6,995 yards in five NFL season, with 164 of those coming in 1952, 1953, and 1955.)
To build the roster of the expansion Cowboys, Dallas was allowed to pick certain players from certain teams per league rules. Founder Clint Murchison selected LeBaron, the Redskins' Pro Bowl quarterback. LeBaron would become the Cowboys' first starting quarterback. Redskins owner George Preston Marshall had forgotten to move LeBaron to the team's "protected" list.
He was the starting quarterback for the Dallas Cowboys for their first three seasons, 1960 to 1962. LeBaron started 10 of 12 games in 1960, with the rookie Don Meredith starting one and Don Heinrich starting the other. He also scored the Cowboys' first-ever touchdown in their first exhibition game against the San Francisco 49ers, on August 6, 1960 in Seattle. LeBaron started 10 of 14 games in 1961, with the young Don Meredith starting the other four. He only started five games in the 1962 season, but split time with Don Meredith almost evenly. He started the first game of the 1963 season, but was replaced permanently by Meredith for the rest of the season, with LeBaron becoming Meredith's backup.
He retired at the end of 1963, after playing 12 seasons, throwing for 13,399 yards and 104 touchdowns. He was selected for the Pro Bowl four times in 1955, 1957, 1958, and 1962. The shortest quarterback to ever be selected to the Pro Bowl, LeBaron was known primarily as a ball-handler and elusive scrambler.
LeBaron became a football announcer for CBS Sports after his NFL career, and worked as an announcer from 1966 to 1971. He had obtained a law degree during his off-seasons from football, and practiced law after his football career. He was also the general manager of the Atlanta Falcons from 1977 to 1982 and executive vice president from 1983 through 1985. LeBaron is an avid golfer and continues to play golf in his retirement.