Ponsonby entered the House of Commons in the 1831 general election, sitting as a Whig for Bletchingley, where he was returned unopposed. He only sat for a short period, vacating his seat in July in favour of Thomas Hyde Villiers, newly appointed as a minister and requiring a seat. In October, he was offered a seat in the pocket borough of Higham Ferrers, which he held until the seat was disenfranchised at the end of 1832. During 1832, he may have spent some time at the British embassy in Russia.