He was made a privy councillor by Charles II, but he soon withdrew with his friend Lord Russell, when he found that the Roman Catholic interest uniformly prevailed.

In January 1681 he carried up to the House of Lords the articles of impeachment against Lord Chief Justice William Scroggs, for his arbitrary and illegal proceedings in the court of King's bench, and later when the king declared his resolution not to sign the bill for excluding the duke of York (afterwards James II), he moved in the House of Commons that a bill might be brought in for the association of all his majesty's Protestant subjects.

[2] He opposed the arbitrary acts of James II until his enemies found an excuse to neutralize him; after an imagined insult by a Colonel Colepepper, Cavendish struck his opponent and was immediately fined the enormous sum of £30,000.

The earl went for a time to Chatsworth House, where he occupied himself with the erection of a new mansion, designed by William Talman, with decorations by Antonio Verrio, James Thornhill, and Grinling Gibbons.

[1] After the revolution, Cavendish was a leading Whig, serving as William's Lord Steward, and was created the Duke of Devonshire (1694) and also Marquess of Hartington in recognition for his services.

His last public service was assisting to conclude the union with Scotland, for negotiating which he and his eldest son, the marquis of Hartington, had been appointed among the commissioners by Queen Anne.