The group was originally composed of four brothers from Piqua, Ohio: John, Herbert, Harry and Donald. They began performing together in the 1920s, and first became commercial successes towards the end of the decade. They were known for their close harmonies and their ability to imitate musical instruments with their voices. Their first big hit was a cover record of the Original Dixieland Jass Band standard "Tiger Rag".
Their early recordings show them as excellent hot jazz vocalists. They were popular radio stars, billed with the subtitle "Four Boys and a Guitar" and announcers commonly explained to listeners that the only instrument was a guitar, as the vocal effects made many listeners think they were hearing a muted trumpet, saxophone, and string bass.
The Brothers appeared in a number of movies through the 1930s, and in addition to their phonograph records as a group, they were paired with other jazz stars of the era such as Louis Armstrong and Bing Crosby for some recordings.
John died in 1936 and was replaced by his father, John Mills, senior. In the 1940s their style changed to emphasize a more sweet rather than hot sound. Eventually their father retired from the group and the three remaining brothers continued on as a trio. They stopped performing when Harry died in 1982.
Some of their later hits include:
- "Paper Doll" (1943)
- "You Always Hurt The One You Love" (1944)
- "Till Then" (1944)
- "Across The Alley From The Alamo" (1947)
- "I've Got My Love To Keep Me Warm" (1949)
- "Daddy's Little Girl" (1950)
- "Nevertheless" (1950)
- "Be My Life's Companion" (1952)
- "Glow Worm" (1952)
- "The Jones Boy" (1954)
- "Cab Driver" (1968)