McDonald was born in Hot Springs, Arkansas. During the early 1930s, he broadcast for the Chattanooga Lookouts, and won the first The Sporting News "Announcer of the Year" award in 1932—a remarkable achievement, considering that the Lookouts were a Class A team. Senators owner Clark Griffith jumped him straight to the big club in 1934, and he immediately became a hit. He was one of the first to use "ducks on the pond" as a term for players on base, and also sung an old country tune, "They Cut Down the Pine Tree", after a big Senators play. He was best known, however, for recreations of road games—a common practice in the 1930s, when line charges were too expensive for live road coverage. For many years, it was common for Senators fans to crowd around McDonald's studio at a drug store on G Street to watch his recreations.
In 1939, he became the first full-time voice of the Yankees and Giants, working the second half of the season alongside a young Mel Allen. In that same year, he aired the opening of the Baseball Hall of Fame on CBS. However, his homespun style didn't play well in New York, and he was back in Washington for the 1940 season.
For the most part, McDonald called losing baseball; the Senators only finished higher than fifth four times during his tenure. However, he was named "Announcer of the Year" again in 1942. During the 1940s, he began calling Washington Redskins and college football games.
McDonald was forced off Senators broadcasts by a sponsor change in 1956, but remained behind the mike for the Redskins. He died at age 59, of a heart attack, while en route by train from New York City to Washington, D.C. (Obituary: New York Times, October 17, 1960)