In 1826 Chichester was elected Whig Member of Parliament for Milborne Port, a seat he held for four years before becoming representative for County Wexford in 1830. The following year, on the occasion of the coronation of William IV, he was created Baron Templemore, of Templemore in the County of Donegall. He was also made a Lord of the Bedchamber in 1835, and in 1837 succeeded this appointment as a Lord in Waiting.
Lord Templemore married Augusta Paget, daughter of Henry William Paget, 1st Marquess of Anglesey, in 1820. He died after a short illness aged 40 at his home of Coombe Bank, Kent, and was buried at nearby Sundridge. His wife outlived him by thirty-five years, dying in 1872.