He represented the latter constituency in the Irish House of Commons until 1799, when he became Earl of Charlemont on the death of his father.

On 12 December 1806, he was elected as an Irish representative peer and assumed his seat in the House of Lords.

[1] In 1837 he was created Baron Charlemont in the Peerage of the United Kingdom, thereby giving him and his descendants an automatic seat in the House of Lords.

He married Anne, the daughter and co-heiress of William Bermingham of Ross Hill, County Galway and Mary Rutledge.

His four children pre-deceased him and he was consequently succeeded in his estate and title by his nephew, James Molyneux Caulfeild.