Lewis was the third son of Sir Edward Lewis, a courtier, and his wife Lady Anne Sackville, daughter of Robert Sackville, 2nd Earl of Dorset and widow of Edward, Lord Beauchamp. His father was of The Van, Glamorgan and Edington Priory, Wiltshirehire and died in 1630.
He was commissioner for assessment for Wiltshire from January 1660 to 1680 and commissioner for militia for Wiltshire in March 1660. He was Justice of the Peace for Wiltshire from July 1660 to June 1688. In 1661 he was re-elected Member of Parliament for Westbury in the Cavalier Parliament.
He was lieutenant-colonel of foot militia for Wiltshire in 1661.
From 1662 to 1663 he was commissioner for corporations. He was Deputy Lieutenant from 1668 to June 1688.
He was commissioner for assessment for Monmouthshire and Glamorgan from. 1677 to 1680. He was r-elected Member of Parliament for Westbury in the two elections of 1679.
He became a colonel in the militia in 1681 and was sheriff from 1681 to 1682.
In 1684 he was freeman of Devizes. In 1685 he was elected Member of Parliament for Westbury again. He was Justice of the Peace for Glamorgan from 1685 to 1696 and commissioner for rebels’ estates in Wiltshire in 1686.
He was displaced as freeman of Devizes by order-in-council in 1687.
He was Justice of the Peace for Wiltshire and Deputy Lieutenant from October 1688 to 1696. He was commissioner for assessment for Monmouthshire, Wiltshire and Glamorgan from 1689 to 1690.
He was re-elected Member of Parliament for Westbury in 1689, 1690, 1695 and 1698. In 1696 he was removed from the lieutenancy for refusing the Association.
He was Justice of the Peace for Glamorgan and Wiltshire from 1700 until his death.
In February 1701 he was elected Member of Parliament for Westbury again. Lewis died in 1706, in his "eighty-third year", and was buried at Corsham.
Cavalier Parliament. Exclusion Bill Parliament. Habeas Corpus Parliament]
In April 1660, he was elected Member of Parliament for Westbury in the Convention Parliament.
