Mrs. Hoyt was born Carrie Knoles in Petersburg, Illinois on October 24, 1866. Her father was a lawyer, newspaper publisher and Civil War veteran. In 1887, the Knoles family moved to San Diego County where her father served as U.S. Commissioner for Southern California, prosecuting smuggling cases. Carrie Knoles met, and in 1888, married her husband, William Hoyt. They had four children.
In 1909, the Hoyts moved to Berkeley. Mrs. Hoyt was elected to the Berkeley City Council in 1923, the first year of the city manager form of government. After the City Manager announced his intention to resign as of January 15, 1947, the Berkeley City Council chose Mayor Fitch Robertson to replace him, which it did on January 20. As the Vice Mayor, 80-year old Carrie Hoyt then assumed the office of Mayor to finish out Robertson's term, thus becoming Berkeley's first female mayor.
Mrs. Hoyt died March 25, 1950 at her home in Berkeley.
Carrie Hoyt's son Ralph E. Hoyt became Alameda County District Attorney, and later, a judge of the Superior Court.