He was the son of Rear-admiral Philip Carteret, the circumnavigator, by his wife Mary Rachel, daughter of Sir John Baptist Silvester, M.D., F.R.S.
(d. 1789), a Frenchman by birth, a Dutchman by education, and physician to the army in the Low Countries, under the Duke of Cumberland, during the War of the Austrian Succession (cf.
She was paid off in 1803, and in 1804 Carteret was appointed to the 18-gun brig Scorpion, in which he was actively employed in the North Sea; and on 11 April 1805 captured a Dutch vessel bound for the West Indies with a cargo of arms and military stores.
In December 1805 he was sent out to the West Indies, where, during the greater part of 1806, he was engaged in watching and sending intelligence of the French squadron under Willaumez, so that it was not till his return to England in the spring of 1807 that he received his commission as post-captain, dated 22 January 1806.
Carteret ran down to engage this, only to find that she was a Portuguese East Indiaman; and meanwhile the disabled French frigate had made good her escape, only to be captured, after very feeble resistance, two days later by the Andromache.