Charles Joseph Byrnes (1835 – 22 October 1917) was an Australian politician.
He was born in Parramatta, the youngest son of Ruth Barber and James Byrnes, a storekeeper and early New South Wales politician. His uncle William was also a member of the Legislative Council.
The younger Byrnes was articled to a solicitor, but chose business over law and took over the family wool mill at Parramatta. He also owned a tweed mill at Granville, and was a long-serving alderman and mayor of Parramatta. In 1874 he was elected to the New South Wales Legislative Assembly for Parramatta. He retired in 1877, was re-elected in 1880, and retired again in 1882. Byrnes died at Parramatta in 1917.