After studying at Eton and Oxford, he succeeded his father as 5th Marquess of Lansdowne (in the Peerage of the United Kingdom) and 6th Earl of Kerry (in the Peerage of Ireland) at the relatively young age of 21 on 5 June 1866. He inherited a vast estate, including Bowood House and great wealth. Three years later, he married Lady Maud Evelyn Hamilton (a daughter of the 1st Duke of Abercorn) and they had two sons and two daughters.
Lord Lansdowne entered the House of Lords as a member of the Liberal Party in 1866. He served in William Gladstone's government as a Lord of the Treasury from 1869 to 1872 and as Under-Secretary of State for War from 1872 to 1874. He was appointed Under-Secretary of State for India in 1880, and having gained experience in overseas administration, was appointed Governor General of Canada in 1883. The present-day town of Lansdowne, Garhwal in Uttarakhand, India, was established in 1887 and named after him.
Yet Lord Lansdowne took the opportunity to travel extensively throughout western Canada in 1885, meeting many of Canada's First Nations peoples. While the railway to British Columbia was not completed, this did not stop the Governor General from travelling throughout the Rockies on horseback and by boat. On his second trip out west, Lord Lansdowne took the new Canadian Pacific Railway, and was the first Governor General to use the line all the way out west.
His experiences in western Canada gave Lansdowne a great love of the Canadian outdoors and the physical beauty of Canada. He was an avid salmon fisherman, and was also intently interested in winter sports. His love of the wilderness and Canadian countryside led him to purchase a second residence on the Cascapédia River in Quebec.
It was with the issue of fishing rights between the United States and Canada that Lansdowne proved himself as an adept statesman, helping to negotiate a peaceful settlement to a potentially serious dispute between both countries. He was also a supporter of scientific development, presiding over the inaugural session of the British Association for the Advancement of Science in 1884.
Lord Lansdowne departed Canada with a true appreciation of the beauty of the wilderness and an equal appreciation of the diversity of Canadian society. He was considered a very able Governor General, and gave his wife a great deal of the credit for his success in Canada. One of her happiest and most successful endeavours while at Rideau Hall was a party she threw for 400 Sunday school children. Lady Lansdowne was decorated with the Order of Victoria and Albert and the Imperial Order of the Crown of India.
In the following years, Lansdowne continued as Lords leader, his stature even somewhat improved by Balfour's resignation and replacement as Tory leader in the commons by the inexperienced Andrew Bonar Law, who had never held cabinet office. In 1915, Lansdowne joined the wartime coalition cabinet of Herbert Henry Asquith as a Minister without Portfolio, but was not given a post in the Lloyd George government formed the following year, despite Conservative preeminence in that government. In 1917, having discussed the idea to colleagues for some time with no response, he published the controversial "Lansdowne Letter," which called for a statement of postwar intentions from the Entente Powers. He was criticized as acting contrary to cabinet policy.
Lord Lansdowne's military secretary, Lord Melgund, benefited greatly from serving the Governor General. He later became Lord Minto and served as Governor General between 1898 and 1904.
When Lansdowne died his estate was probated at 1,044,613 pounds sterling of land, with another 233,888 pounds in other assets.