As a.d.c. to the Duke of Rutland, lord lieutenant of Ireland (an office once held by his uncle), Hobart sat in the Irish parliament:
Mr Hobart’s voice is naturally good, clear, full, well-toned and with sufficient compass, but he much injures it by a species of affectation that reduces it nearly to a feminine lisp, adopted perhaps from his familiar intercourse with pretty ladies and pretty gentlemen.
Rutland had recommended him to Pitt for a vacant seat for Lincoln in 1786, but too late. On 16 Jan. 1788, writing after Rutland’s death to Pitt for support for his application for a lieutenant-colonelcy, Hobart maintained that his personal and political attachment was to him, although ‘my own immediate connexions lead me to a different channel’. (His father acted with opposition.) In November 1788 the viceroy reported that Hobart wished to have a seat at Westminster, meaning to ‘devote every faculty’ to Pitt. Returned for Bramber on the Rutland interest before the year was out, he duly voted with administration next session. He was then, at the instigation of the Irish viceroy Lord Buckingham, appointed his chief secretary, as also to Lord Westmorland, his successor in Ireland. Buckingham thought he had ‘quickness, parts, and the most intimate knowledge of every man in Ireland’. Lady Holland who found him ‘pleasing, sensible and well-looking, the finest teeth possible’, reported ‘he exhibited his high sense of a point d’honneur in marrying Mrs Adderley. When her husband died Lord Hobart fulfilled the promise.’
Hobart returned from Ireland to secure his election for Lincoln, which was contested, in 1790; but his duties took him back to Dublin. In his absence he was listed hostile to the repeal of the Test Act, April 1791. In November 1791 he arrived in London to discuss Catholic relief in Ireland with ministers. Richard Burke, his former schoolfellow, was disappointed in his hope of talking Hobart into an enlightened view of the subject. Burke’s father was not surprised, regarding Hobart as the creature of the Beresford party in Ireland: ‘Mr Hobart owes only the accident of his birth to this country— in connexions, in habits and in the turn and genius of his politics is purely Irish’. In April 1792 he returned to England to influence government against endangering the protestant ascendancy. During this visit he spoke at Westminster, in favour of the abolition of the slave trade, 27 Apr., and in disparagement of Grey’s intended motion for parliamentary reform, with reference to Ireland, 30 Apr. In the spring of 1793, without concealing his distaste for it, he steered the Irish Catholic relief bill through the Dublin parliament. He reappeared at Westminster, 16 May, to obtain leave for goods legally imported into Ireland from other continents to be exported thence to Great Britain. In October he was chosen governor of Madras. Quitting Dublin on 2 Dec. 1793, he obtained an assurance that he would succeed as governor-general of India after Cornwallis and Sir John Shore. His Irish services were rewarded with the reversion of the office of clerk of the common pleas in the Irish exchequer held by Lord Clonmell.
Hobart’s excursion to Madras proved damaging to his reputation. His Carnatic policy was objected to by Sir John Shore the governor-general and he was recalled by the court of directors. He was compensated for the loss of supreme power by a pension of £1,500 p.a., reduced ostensibly because his lucrative sinecure had now fallen in to him. His friend and agent John Sullivan had at first failed to induce Dundas to procure a peerage for him, but on his return home in 1798 he was summoned to the Lords in his father’s barony.