He was born in Cornwall to miner Samuel Meyn Barnes and Jane Mitchell.
He was a timber worker, and after suffering a serious leg injury emigrated to Victoria around 1886.
He held a supervisory position during the construction of the Long Tunnel mines, and served on the Walhalla Shire Council from 1905 to 1910 (president 1909–10).
In 1910, Barnes was elected to the Victorian Legislative Assembly for Walhalla as a Liberal, later transitioning to the Nationalist Party.
He lost his seat to a Country Party candidate in 1927 and retired from politics.