James Albert Dimmitt (21 June 1888 – 29 January 1957) was an Australian politician who was a Liberal Party member of the Legislative Council of Western Australia from 1938 to 1953.
Dimmitt was born in Melbourne, and arrived in Western Australia in 1911, where he began working as a salesman.
His own company, Armstrong Dimmitt Ltd., sold motor vehicle parts and accessories.
Dimmitt was elected to parliament in 1938, representing Metropolitan-Suburban Province.
He was appointed chairman of committees in the Legislative Council in 1946, replacing James Cornell.