He joined the service in 1731, was commissioned lieutenant on 16 September 1740, and promoted commander on 20 August 1746, being appointed to the bomb Granado 8 which he retained until the late summer of 1747.
He was posted captain of the Flamborough 20 for purposes of rank on 20 April 1748, had the Squirrel 20 briefly before she was sold out of the Navy, and then joined the Glasgow 20, going out to Africa in May of the following year and from thence to the West Indies prior to being paid off in June 1752. In December 1753 he recommissioned the Experiment 20 for service in the Bristol Channel, and in July 1755 he recommissioned the Prince Edward 44 for service in the same waters, retaining her for the next two years.
In January 1757 he commissioned the new Preston 50, initially engaged in cruising and then going out with the Levantine trade in December, being rewarded by the Levant Company for his safe delivery of a convoy. Later service was in the Channel, and he flew the broad pennant of Commodore William Boys at the blockade of Dunkirk during the summer of 1759 and in North America during the following year. He appears to have retained the Preston through to the end of hostilities in 1763.
From 1767-70 he had the Chatham-based guard ship Augusta 64, being succeeded in the command by his namesake Captain Thomas Evans with whose service his own was often confused.
He raised a commodore’s pennant at Portsmouth aboard the Invincible 74, Captain Anthony Parrey, in early 1778, and was the third in command of Vice-Admiral Hon John Byron’s fleet which left England for North America on 9 June 1778. Having lost her mainmast in the storms that disrupted the fleet’s passage the Invincible was obliged to make for Newfoundland where Evans had been appointed second in command. Whilst on that station he was ordered to take possession of the islands of St. Pierre and Miquelon from France, flying his broad pennant aboard the Romney 50, Captain George Montagu, a feat he achieved without resorting to bloodshed. The nine hundred or so inhabitants were put on transports for France and their infrastructure was destroyed.
He was raised to flag rank on 29 March 1779, became a vice-admiral on 26 September 1780, and briefly commanded in the Downs with his flag aboard the storeship Dromedary, Captain William Denne, through the winter of 1780-1 in the absence of Vice-Admiral Francis William Drake. He then saw duty during 1781-2 at Spithead as second-in-command to the commander-in-chief of the Portsmouth station, Admiral Sir Thomas Pye, with his flag aboard the receiving ship and Spanish prize Diligente 70, Captains Anthony Hunt and John Knowles. In this capacity he sat on the court martial into the loss of the Royal George on 29 August 1782.
Evans was promoted to the rank of admiral on 1 February 1793, and died at Feltham, Middlesex, on 8 July 1794.