James Byrnes may refer to:
- James Byrnes (Australian politician) (1806–1886), New South Wales politician
- James Byrnes (sailor) (1838–1882), Irish sailor and Medal of Honor recipient
- James F. Byrnes (1882–1972), American politician and Supreme Court Justice from South Carolina
- Jim Byrnes (baseball) (1880–1941), American baseball player
- Jim Byrnes (actor) (born 1948), American actor and blues musician
- Jim Byrnes (producer), American television producer and writer.