The son of Thomas Gilbert ofRatcliffe,Buckinghamshire, a captain in theRoyal Marines, by Elizabeth, daughter of William Long Nathaniel Hutton, rector ofMaids Moreton, Buckinghamshire, was born nearBurnham Beeches, Buckinghamshire, 14 May 1786, and educated atManchester Grammar School from 1800. He was nominated to a school exhibition, and matriculated atBrasenose College, Oxford, on 30 May 1805. At the Michaelmas examination of 1808 he was placed in the first class inliteris humanioribus, one of his four companions beingRobert Peel. He graduated B.A. 16 January 1809, and succeeded to one of Hulme's exhibitions on 8 March following. Having been elected to a fellowship, he proceeded M. A. 1811, andB.D. 1819.
He was actively engaged for many years as a college tutor, and in 1816–18 was a public examiner. On the death ofFrodsham Hodson in 1822, he was elected Principal of Brasenose on 2 February, and took his D.D. degree on 30 May. From 1836 to 1840 he wasVice-Chancellor of Oxford University. On the death ofPhilip Shuttleworth he was nominated to thebishopric ofChichester, 24 January 1842, and consecrated atLambeth Palace on 27 February.
Gilbert took much interest inLancing College and other educational institutions. Ofhigh church opinions himself, he was averse to Catholic ceremonials. He took proceedings in the 1850s againstJohn Mason Neale, Warden ofSackville College; and on 14 October 1868 he interdictedJohn Purchas fromritualism in services at St James's Chapel, Brighton. This latter case led to much litigation, and eighteen works were printed in connection with the matter.
Gilbert was married on 31 December 1822 to Mary Anne, only surviving child of the Rev. Robert Wintle, vicar ofCulham,Oxfordshire. They had eleven children. Mary Anne died in the Bishop's Palace at Chichester on 10 December 1863.
Gilbert died of paralysis at the Bishop's Palace in Chichester on 21 February 1870, and was buried inWesthampnett Church,Sussex, on 25 February.