The title was created for a second time in 1689 in favour of William Bentinck, the Dutch favourite and close adviser of King William III. He was made Baron Cirencester and Viscount Woodstock at the same time he was given the earldom, also in the Peerage of England.
The first Earl was succeeded in 1709 by his son from his first marriage, Henry Bentinck, who became the second Earl. He had represented Southampton and Hampshire in the House of Commons. In 1716, he was created Marquess of Titchfield and Duke of Portland in the Peerage of Great Britain.
His grandson, William Cavendish-Bentinck, 3rd Duke of Portland, was a noted politician. He was Prime Minister in 1783 and from 1807 to 1809, and he also served as Home Secretary and as Lord President of the Council. In 1801, he assumed by Royal licence the additional surname of Cavendish (to form Cavendish-Bentinck). He was the husband of Lady Dorothy Cavendish, daughter of William Cavendish, 4th Duke of Devonshire, and was a descendant on his mother's side of Henry Cavendish, 2nd Duke of Newcastle-upon-Tyne.
The third Duke was succeeded by his eldest son, William Bentinck, 4th Duke of Portland. The fourth Duke was also a politician and served as Lord Privy Seal in 1827 and as Lord President of the Council from 1827 to 1828. He married Henrietta Scott, daughter of Major-General John Scott, in 1795 and assumed by Royal licence the same year the additional surname of Scott in the manner of Cavendish-Bentinck. His eldest son and heir apparent, William Cavendish-Scott-Bentinck, Marquess of Titchfield, represented two constituencies in Parliament but died unmarried in 1824, 15 years before his father. The fourth Duke was therefore succeeded by his second son, William Cavendish-Scott-Bentinck, 5th Duke of Portland. The fifth Duke is remembered as a capable architect and engineer but eccentric, who excavated an underground art gallery and library under his estate at Welbeck Abbey.
The fifth Duke died unmarried and was succeeded by his first cousin once removed, William Cavendish-Bentinck, 6th Duke of Portland, who was the only son from the first marriage of Lieutenant-General Arthur Cavendish-Bentinck, younger son of Lord Charles Bentinck, the third son of the third Duke. Charles' first son, also named Charles, was a maternal great-grandfather of Queen Elizabeth II. In 1880, the sixth Duke also succeeded his stepmother as second Baron Bolsover. He was a Conservative politician and served as Master of the Horse from 1886 to 1892 and from 1895 to 1905.
His eldest son, William Cavendish-Bentinck, 7th Duke of Portland, was also a Conservative politician and served as a Junior Lord of the Treasury from 1927 to 1929 and in 1932. The seventh Duke had no sons and was succeeded by his third cousin, Ferdinand Cavendish-Bentinck, 8th Duke of Portland, a great-grandson of Major-General Lord Frederick Cavendish-Bentinck, fourth son of the third Duke. The barony of Bolsover became extinct upon the death of the seventh Duke.
The eighth Duke was a colonial administrator in British Kenya and served as Speaker of the Legislative Assembly of Kenya. He was childless and was succeeded by his younger brother, Victor Cavendish-Bentinck, 9th Duke of Portland, a diplomat who had served as British Ambassador to Poland. The ninth Duke's only son, William James Cavendish-Bentinck (1925–1966), died before him without issue. Upon the ninth Duke's death in 1990 at the age of 93, the dukedom of Portland and the marquessate of Titchfield became extinct.