Jacobs was born as Clara Belle Harrod in Union, Ohio, on 9 September 1866 as the daughter of Levi and Susan (née Foght) Harrod. On 8 February 1887, she married Alva Warren Jacobs, who worked as a barber.
Jacobs and her husband had no biological children, but they adopted a daughter, Beatrice, born in 1902 or 1903. She was widowed on 29 November 1938. At the age of 99, she baked her own birthday cake, and she could still walk aged 106. As a centenarian, she was reported to have a sharp mind.
In April 1975, Jacobs’ nursing home closed down, and she had to be moved to a new facility in Spencerville, Ohio. She died at 10:20 a. m. on 18 October 1977 at the age of 111 years, 39 days; her funeral was held three days later.