Thomas Johnes (died c. 1734) of Llanfair Clydogau, Cardiganshire and Dolau Cothi, Carmarthenshire, was a Welsh Whig politician who sat in the House of Commons from 1713 to 1715.
Johnes was the only surviving son of Thomas Johnes of Llanfair, Cardiganshire, and his wife Anne Lloyd, daughter of David Lloyd of Crymlyn, Monmouthshire.
He married Jane Herbert, daughter of William Herbert of Hafod Uchdryd, Llanfihangel-y-Creuddyn, Cardiganshire and then as his second wife, Blanche Van, daughter of David Van of Llanwern, Monmouthshire.
He stood as a Whig for Parliament at Cardiganshire at the 1708 British general election but was defeated and was unsuccessful in two succeeding petitions.
At the 1713 general election he was returned as Member of Parliament for Cardiganshire, but lost the seat in 1715.