Son of Richard Robartes (d.1634). Matriculated from Exeter College, Oxford in 1625. He succeeded his father as 2nd [[personal title::Baron Robartes of Truro in 1634. He fought at Edgehill on the parliamentarian side during the Civil War. In 1643 his estate was sequestered and given by the king to Sir Richard Grenvile. After the Restoration he was admitted to the privy council and was made Teasury commissioner and deputy lieutenant of Ireland. He became lord lieutenant of Ireland in 1669. In 1679 he was created Viscount Bodmin and earl of Radnor.
Developed the library at Lanhydrock House, Cornwall with Richard Robartes.
- Duffin, Anne. "Robartes, John, first earl of Radnor (1606–1685), politician and army officer." Oxford Dictionary of National Biography.
- Barker, N. Treasures from the libraries of National T rust country houses, New York, 1999, no 45.
- Keep, D. Works by Zurich reformers in the library at Lanhydrock, National Trust Yearbook 1976-7, 73-80.
- Purcell, M. The library at Lanhydrock, The Book Collector 54 (2005), 195-230.