He entered the navy in November 1789, served on the Mediterranean, home, and Newfoundland stations, and in 1796 was in the Royal George, flagship of Lord Bridport, by whose interest he was made lieutenant, on 19 August, to the Incendiary fireship.
During 1804–1805–6, he commanded various small vessels off Boulogne and the north coast of France, and in December 1806 was appointed to the Grasshopper brig for service in the Mediterrean.
Lord Collingwood officially reported the affair as ‘an instance of the zeal and enterprise which marked Searle's general conduct.’ On 4 April 1808, in company with the Alceste and Mercury frigates, he assisted in destroying or capturing a convoy of merchant vessels at Rota, near Cadiz, after dispersing or sinking the gunboats that escorted them, and silencing the batteries of Rota, which protected them.
This last service was performed by the brig alone ‘by the extraordinary gallantry and good conduct of Captain Searle, who kept in upon the shoal to the southward of the town so near as to drive the enemy from their guns with grape from his carronades, and at the same time kept in check a division of the gunboats that had come out from Cadiz to assist the others engaged by the Alcestes and Mercury.
In 1818–21 he commanded the Hyperion frigate in the Channel (in attendance upon George IV) and in a voyage to South America, whence he brought back specie to the amount of half a million sterling.