Waldegrave was the second son of John Waldegrave, 3rd Earl Waldegrave and Elizabeth (née Gower). Joining the navy at age 13 in 1766, Waldegrave rose rapidly through the ranks, receiving his own command, the Zephyr in 1775, and being promoted to Vice-Admiral in 1795. He was the third in command on the British side at the Battle of Cape St. Vincent in February 1797, and was offered a baronetcy for the role he played in the battle. Waldegrave declined the offer (on the grounds that as a son of an earl, he already held a higher station), and was appointed the Governor of Newfoundland, Saint-Pierre and Miquelon, on 16 May 1797.
During Waldegrave’s time as Governor, he was chiefly concerned with military matters, as a French squadron had burned Bay Bulls just a year prior, and Newfoundland was still quite exposed. Another key problem was desertion, as soldiers deserting to Newfoundland were generally sheltered by the island’s inhabitants. A naval mutiny occurred shortly after Waldegrave’s appointment and had to be stopped; Waldegrave also took steps to ensure that soldiers garrisoned in St. John’s did not try anything similar. In military matters, he was often at odds with his commander, Lieutenant-Colonel Thomas Skinner.
Waldegrave made several attempts to restrict the power of the merchants on Newfoundland, and also to bring law and order to the island. Although his efforts against the merchants were largely ineffective, Waldegrave was successful in having a chief justice appointed who would reside year round. Waldegrave also undertook various humanitarian projects, especially to help the poor. He established a “Committee for the Relief of the Poor,” and contributed generously to the fund. Between 1797 and 1798, nearly 300 people received assistance from this fund.
Waldegrave finished his term as governor in 1800 and was created an Irish peer as Baron Radstock. In 1802, upon his retirement Waldegrave was promoted to full admiral. In 1815 he was appointed a Knight Grand Cross of the Order of the Bath.
Waldegrave was married in 1785 to Cornelia Jacoba van Lennep. They had three sons and six daughters:
**V-Adm. Granville George Waldegrave, 2nd Baron Radstock (1786–1857), married Esther Paget and had issue
**Hon. Emily Susanna Laura Waldegrave (5 November 1787 – 12 April 1870), married Nicholas Westby
**Maria Waldegrave (26 December 1788 – 1791)
**Hon. Isabella Elizabeth Waldegrave (18 August 1792 – 21 October 1866)
**Hon. Harriet Ann Frances Waldegrave (20 October 1793 – 26 July 1880), unmarried
**Capt. Hon. William Waldegrave (7 June 1796 – 29 December 1838), married Amelia Allport
**Hon. Caroline Waldegrave (4 October 1798 – 7 January 1878), married Rev. Carew Anthony St John-Mildmay and had issue
**Hon. Augustus Waldegrave (4 February 1803 – November 1825), killed in a hunting accident near Mexico City
**Elizabeth Frances (24 November 1799 – August 1800)