From 1943 through 1951, Kerr played for the New York Giants (1943–1949) and Boston Braves (1950–1951). A native of Astoria, New York, in the New York City borough of Queens, he batted and threw right-handed. Despite the fact that he hit a home run in his first major league at-bat on September 8 of his debut season, Kerr was known mostly as a slick fielder with a very light battalion
From 1946 to 1947, he played 68 consecutive games without committing an error, which was a major league record at the time.
His most productive offensive season came in 1947, when he recorded a career-high.287 average. An All-Star in 1948, he also received minor consideration in the National League Most Valuable Player voting in 1945 and 1946.
Before the 1950 season, Kerr was sent to the Boston Braves along with Willard Marshall and Sid Gordon. The trade brought Alvin Dark and Eddie Stanky to the Giants.
Kerr was a regular in his first year for the Braves, but he saw little action in 1951 and retired at the end of the season after playing his final game on September 30.
In a nine-season career, he was a.249 hitter with 31 home runs and 333 runs batted in in 1067 games played. Kerr worked for the New York Mets from 1975 through 2000 as a special assignment scout. He died in New York City after a short illness, one day after his 84th birthday.