Marsh was the starting running back at Wallowa High School, contributing to the team's Tu-Valley football co-championship in 1957. Which was a three way tie with Enterprise and Union, but only Wallowa advanced to the state playoffs after a vote by the league's school superintendents. As a sprinter and long jumper in track, Marsh helped Wallowa win the 1957 State Class "B" title. During those years, he developed a famous rivalry with Jim Puckett from Cove High School. The two raced in the 100 yard dash competition, with Puckett winning every contest, making Marsh the 100-yard dash state runner up three times. The 100-yard dash is no longer practiced and was run from 1927 to 1977.
Marsh was signed as an undrafted free agent by the Dallas Cowboys after the 1961 NFL Draft, because they were impressed by his speed. He also was a powerful player, earning the nicknames "Moose" and "Forward Marsh". He started his career as a wide receiver and special teams player. He was eventually moved to fullback to take advantage of his size and speed, while splitting time with J. W. Lockett. He led the team in kickoff and punt returns. He set franchise records with a 71-yard run from scrimmage and a 79-yard kickoff return. In 1962, he played fullback alongside Don Perkins, ranking seventh in the NFL with 802 yards and a 5.6-yard average per carry. That year, he set a franchise record with an 85-yard touchdown reception against the Los Angeles Rams and also broke his franchise record for the longest kickoff return with 101 yards, which was broken by Alexander Wright 29 years later in 1991. The play came against the Philadelphia Eagles, when the Cowboys became the first NFL team in history to produce two 100-yard plays in the same game: a 100-yard interception return for a touchdown by strong safetyMike Gaechter and the 101 yard kickoff return for a touchdown by Marsh. In 1964, he was moved to halfback, with Perkins taking over the fullback position. Marsh's production regressed during the following years, while alternating with Jim Stiger. On September 9, 1965, he was traded to the Detroit Lions, after the team acquired fullback J.D. Smith. The Cowboys selected Walt Garrison with the fifth round draft choice they obtained in the transaction.
Detroit Lions
Playing as a fullback in 1965, he led the Detroit Lions in rushing and touchdowns. On August 19, 1968, he was traded to the Atlanta Falcons in exchange for a conditional 1969draft pick.
Atlanta Falcons
On September 2, 1969, he was waived by the Atlanta Falcons before the start of the season.
Personal life
His brother Frank also went on to play professional football and then into professional basketball. Marsh died on November 2, 1992, after suffering a series of strokes, because of his diabetes condition.