Krumgold was born in Jersey City, New Jersey, and was immersed in the world of movies from a young age: his father operated movie theatres.

He graduated from New York University, and worked for MGM as a scriptwriter.He married Helen Litwin in 1947; they had one son, Adam, and lived in Greenwich Village, and Hope, New Jersey.

He was hired by the United States Department of State to make a film about Hispanic workers in rural America.The film was created in 1953, and shares a title with Krumgold's first Newbery Award-winning novel, ...And Now Miguel. Six years later, Krumgold's novel Onion John, a story about an eccentric immigrant in small-town New Jersey, also won the Newbery Medal.

Krumgold traveled extensively throughout the world, living in several places including California, Paris, and Rome. From 1947 to 1951, he lived and worked in Israel making movies that marked the founding of modern-day Israel.

Although Krumgold is probably remembered most for the two Newbery winners, he also wrote a number of other novels and movie scripts.

• Seven Miles from Alcatraz - a 1942 movie
• Dream No More - a 1953 movie
• The Autobiography of a Jeep - a film produced in 1943 for the United States Office of War Information
• Henry 3 - a children's novel published in 1967
• The Most Terrible Turk: A Story of Turkey - a children's novel published in 1969
• Sweeney's Adventure - a children's novel published in 1942
• Thanks to Murder - an adult novel published in 1935