A barrister, writer, and civil servant who was Permanent Under-Secretary of the India Office, he was educated at Harrow School and Balliol College, Oxford, where Algernon Charles Swinburne and Charles Bowen were his contemporaries. He graduated BA in 1861. At his father's home he met many distinguished men, including Lord Robert Cecil (afterwards Prime Minister Lord Salisbury), who became a lifelong friend. His friends in literary and dramatic circles included William Makepeace Thackeray, Edward Bulwer-Lytton, Matthew Arnold, Anthony Trollope, W. S. Gilbert, Arthur Sullivan, Edmund Yates, and others. Following his father's death in 1874 he gave up the law in favour of literature and the theatre. Merivale wrote many farces and burlesques. For John Hollingshead he produced The Lady of Lyons Married and Settled performed at the Gaiety Theatre (5 October 1878), and Called There and Back (15 October 1884). The Butler (1886) and The Don (1888) were both written for the actor J. L. Toole. In writing The Don, and other works, Merivale was assisted by his wife, Elizabeth, the daughter of John Pittman, whom he married in London on 13 May 1878.
Suffering from depression for many years, following a breakdown in 1879 he went to Australia on the advice of his physician, and then returned with his health recovered, only to discover that the power of attorney he had left with a defaulting solicitor had cost him his entire fortune.
A few years before his death Merivale became a Roman Catholic. He died suddenly of heart failure on 14 January 1906 at 69 Woodstock Road, Acton, Middlesex, and was buried in his father's grave in Brompton Cemetery. He had no children and his widow was granted a civil-list pension of £50 in 1906.