Evans first known service was as an able seaman in home waters aboard the Revenge 70, Captain Robert Trevor, from the summer of 1733 until the summer of 1734 when he moved to the Dunkirk 60, Captain Digby Dent, being taken into the midshipmen?s berth in July 1736 when she sailed out to Jamaica. In July 1738 he removed with Captain Dent to the Hampton Court 70, seeing further service in the West Indies.
He was commissioned lieutenant on 16 September 1740, and promoted commander on 20 August 1746 with his appointment to the bomb Granado 8. On 21 January 1747 he captured the Calais privateer Marianne 10 after an hour?s action, inflicting casualties of eight men killed and fifteen wounded from her crew of eighty, and taking his prize into the Humber. He retained the Granado until the late summer of that year.
Evans 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, being sent from Plymouth in March 1755 to look into Brest, and in July he was appointed to the Prince Edward 44 at Sheerness 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 the convoy. On 28 February 1758 he was with Admiral Henry Osborn when that officer fell in with three French sail of the line and a corvette off Cape de Gata on the south-east tip of Spain, and the Preston assisted the Revenge 64, Captain John Storr, in the capture of the Orph?e 64. In June he was at Leghorn, and he was back in England by the following year to fly the broad pennant of Commodore William Boys at the blockade of Dunkirk during the summer of 1759 and in North America during 1760. He thereafter 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.
In early 1778 he raised a commodore?s pennant at Portsmouth aboard the Invincible 74, Captain Anthony Parrey, and was the third in command of Vice-Admiral Hon John Byron?s fleet which left England for North America on 8 June . Having lost her mainmast in the storms that disrupted the fleet?s passage, the Invincible was obliged to make for Newfoundland where Evans became the second in command. Whilst on that station he was ordered to take possession of the islands of St. Pierre and Miquelon from France, and flying his broad pennant aboard the Romney 50, Captain George Montagu, this was a feat he achieved on 14 September without resorting to bloodshed. The nineteen hundred or so inhabitants were put on transports for France and their infrastructure was destroyed, whereupon the Invincible returned to Portsmouth at the end of November under jury masts in attendance of the Newfoundland convoy.
In February 1779 Evans raised his commodore?s broad pennant on the Sandwich 90, Captain Richard Edwards, as commander-in-chief at Portsmouth in the absence of Admiral Sir Thomas Pye who had gone ashore for his health. He was promoted rear-admiral on 29 March, and in January 1780 his flag was hoisted aboard the Arrogant 74, Captain John Cleland, as commander-in-chief in Pye?s absence once more. In early September he briefly flew his flag at Portsmouth aboard the Victory 100, Captain Samuel Clayton, when the commander-in-chief of the Channel Fleet, Admiral Sir Francis Geary, resigned his position through ill-health, but when Vice-Admiral George Darby arrived to take over the fleet a week later Evans transferred to the Diligente 70, Captain Anthony Hunt.
He became a vice-admiral on 26 September 1780, and from that month commanded the Downs station in the absence of Vice-Admiral Francis William Drake with his flag aboard the storeship Dromedary, Captain William Denne. He then returned to Portsmouth at the beginning of March 1781 to temporarily replace Pye with his flag aboard the receiving ship Diligente 70, Captains Anthony Hunt and John Knowles, and whilst again commanding at Spithead through July and August 1782 he sat on the court martial into the loss of the Royal George on 29 August. At the end of November he struck his flag to go on a month?s leave.
Evans was promoted to the rank of admiral on 1 February 1793, and he died at Feltham, Middlesex, on 15 July 1794.