On 14 August 1850, Cavendish-Bentinck married Prudentia Penelope Leslie (d. 1896), the daughter of Col.
Charles Powell Leslie II.
Together, they had two sons and two daughters:
Christina Anne Jessica Cavendish-Bentinck (d. 1912), who married Sir Tatton Sykes, 5th Baronet (1826–1913), and was the mother of Sir Mark Sykes, 6th Baronet (1879–1919).

William George Cavendish-Bentinck (1854–1909), who married Elizabeth Livingston (1855–1943), granddaughter of Maturin Livingston (1769–1847), in 1880.

William George Frederick Cavendish-Bentinck (1856–1948), who was the father of the 8th Duke of Portland, and the 9th Duke of Portland.

Mary Venetia Cavendish-Bentinck (1861–1948), who married John Arthur James (1853-1917) and was godmother to Queen Elizabeth the Queen Mother.

In 1889, Cavendish-Bentinck was named by rentboy John Saul in his police statement as a client of the infamous male brothel at the heart of the Cleveland Street Scandal.

Cavendish-Bentinck purchased Branksea Castle on Brownsea Island in 1873 and introduced Jersey cows and developed agriculture on the island.
 He died there in April 1891, aged 69.
His wife survived him by five years and died in June 1896.
On 14 August 1850, Cavendish-Bentinck married Prudentia Penelope Leslie (d. 1896), the daughter of Col. Charles Powell Leslie II. Together, they had two sons and two daughters:
Christina Anne Jessica Cavendish-Bentinck (d. 1912), who married Sir Tatton Sykes, 5th Baronet (1826–1913), and was the mother of Sir Mark Sykes, 6th Baronet (1879–1919).
William George Cavendish-Bentinck (1854–1909), who married Elizabeth Livingston (1855–1943), granddaughter of Maturin Livingston (1769–1847), in 1880.
William George Frederick Cavendish-Bentinck (1856–1948), who was the father of the 8th Duke of Portland, and the 9th Duke of Portland.
Mary Venetia Cavendish-Bentinck (1861–1948), who married John Arthur James (1853-1917) and was godmother to Queen Elizabeth the Queen Mother.
In 1889, Cavendish-Bentinck was named by rentboy John Saul in his police statement as a client of the infamous male brothel at the heart of the Cleveland Street Scandal.
Cavendish-Bentinck purchased Branksea Castle on Brownsea Island in 1873 and introduced Jersey cows and developed agriculture on the island.  He died there in April 1891, aged 69. His wife survived him by five years and died in June 1896.
George Cavendish-Bentinck