Reynell was the eldest son of Sir Richard Reynell of East Ogwell, Devon and his wife Mary Reynell, daughter of Richard Reynell of Creedy Widger. In 1647 he was Justice of the Peace He succeeded to the family estates on the death of his father in 1648.
He was educated at Exeter College, Oxford in 1640 and entered Middle Temple in 1641.
In 1649 he was called to the Barometer Reynell was Justice of the Peace for Devon again and was commissioner for assessment for Devon in 1652. He was Justice of the Peace for Devon again in 1653 and remained in post until 1660.
He was re-elected Member of Parliament for Devon in 1656 for the Second Protectorate Parliament.
He was commissioner for assessment in 1657 and commissioner for militia in 1659. In 1659 he was elected Member of Parliament for Ashburton in the Third Protectorate Parliament.
Reynell was commissioner for assessment from January 1660 to 1663 and commissioner for militia in March 1660. He became Justice of the Peace for Devon again in August 1660 until 1676.
In 1667 he was commissioner for inquiry into the Newfoundland government.
He was commissioner for assessment from 1673 to 1680 and commissioner for recusants for Devon in 1675. From 1677 to 1678 he was High Sheriff of Devon. He was elected Member of Parliament for Ashburton again for the two parliaments of 1679 and in 1681.
In May 1685, he was taken into custody prior to the Duke of Monmouth’s invasion.
He was Justice of the Peace for Devon again from 1687 until his death. In March 1688 he was commissioner for inquiry into recusancy fines for Devon, Dorset and Cornwall and from May to October 1688 he was Deputy Lieutenant.
He was alderman for Totnes from April to October 1688. In 1689 he was elected Member of Parliament for Ashnurton again.
He was commissioner for assessment from 1689 to 1690.
Reynell died at the age of 73 and was buried at East Ogwell on 1 March 1698.
In 1654, he was elected Member of Parliament for Devon for the First Protectorate Parliament.
