Sackville was first recorded as a cricketer in the 1734 season when he and his brother Lord Middlesex played for Kent v Sussex at Sevenoaks Vine on Friday 6 September. On 20 August 1735, Sackville again captained Kent to victory against Sir William Gage's Sussex at Sevenoaks Vine. Shortly afterwards, the London Evening Post speculated that "the Conqueror" between the Kent and Sussex teams would be played in a few days, but there is no record of a further match. Sackville became the main patron of the Kent team and captained the side in many matches until 1745 at least, but he is not mentioned in the sources after that. In 1739, Sackville played for London Cricket Club which was having selection problems at the time. In the 1744 English cricket season, Lord John challenged an All-England side to play against his Kent team and Kent won the game with one wicket to spare, largely thanks to Sackville himself taking a memorable catch to dismiss Richard Newland. The match details were recorded and preserved in what is now cricket's second oldest known scorecard. In 1745, Sackville wrote a letter to the Duke of Richmond after Sussex had lost to Surrey and said: "I wish you had let Ridgeway play instead of your stopper behind it might have turned the match in our favour". Evidently, Sackville had wagered on Sussex to win.
Sackville was a notorious rake in his salad days. He was compelled to marry Lady Frances Leveson-Gower, daughter of John Leveson-Gower, 1st Earl Gower and sister of the Duchess of Bedford in 1744, after she gave birth to his child at Woburn. They eventually had issue two sons and one daughter. The couple's parents were furious, and the Prince of Wales compensated Sackville for any loss of income, making him a lord of his bedchamber in 1745, and thus securing him as a recruit to his party. Their son, John Frederick, later 3rd Duke of Dorset, was a member of the Hambledon Club and a leading supporter of cricket in the latter half of the eighteenth century. Sackville's son-in-law, the 8th Earl of Thanet, was an early member of the Marylebone Cricket Club. His grandsons John Tufton and Henry Tufton were noted amateur players at the end of the 18th century. Sackville was also disappointed when Lord Wilmington the late Prime Minister declined to leave him his Sussex estates, worth £3-£4,000 a year. It is not clear if Wilmington's decision was made because of Sackville's messy private life, or his political inconstancy. He was also a coward, and refused to join the Guards when sent abroad. Finally, he was committed to a private lunatic asylum circa 1746, then sent abroad to exile on a very small allowance in Lausanne where Lord Shelburne met him in 1760, and commented on his dirty condition but lucid conversation. According to his descendant Robert Sackville-West, 7th Baron Sackville in his book Inheritance he became insane later in life, dying in Geneva, Switzerland, aged 52. However, his brother lived long enough to allow John Philip's son to inherit his title and become the next Duke of Dorset.
