Born the son of Thomas Dundas of Fingask, Dundas was educated at Edinburgh High School and entered the army in 1766, rising to Major of the 65th Foot. He was elected Member of Parliament for the Stewartry of Orkney & Shetland in 1771 retaining the seat until 1780. As Lieutenant-Colonel of the 80th Foot he saw action in the American War of Independence, serving under Benedict Arnold in the raid against Richmond 5–7 January 1781. Under Arnold & Phillips, he was present at the capture of Williamsburg 18 April, Blandford 25 April, the attack on Osborne’s wharf 27th, & Manchester 30th. Then he passed under the command of Cornwallis. He commanded the Left Wing at Green Spring6 July. With Tarleton he was bottled up by the Marquis de Choisy at Gloucester during the Siege of Yorktown 6–20 October. Assigned as joint commissioner for carrying out the capitulation, he was made Prisoner of War after the fall of Yorktown. Promoted Colonel 20 November 1782, after repatriation he was appointed to the board of commission in 1782 to examine claims for compensation to those "who having remained loyal to the mother country, had suffered in their rights, properties and profession". Dundas married Lady Elizabeth Eleanora Home, daughter of Alexander, ninth Earl Home, on 9 January 1784. He was elected MP for Orrkney again in 1784 and sat until 1790. He was briefly Lieutenant Governor of Guernsey in 1793. Promoted Major-General on 12 Oct 1793, after the outbreak of the Wars of the French Revolution he served in the West Indies, commanding the 2nd Brigade under Charles Grey in Barbados 1794. He served in the 2nd Invasion of Martinique, February and commanded the military forces under John Jervis in the invasion of Guadeloupe, landing on 12 April and capturing Grand-Terre. After accepting the French surrender on 20 April he was made Governor of Guadeloupe, but died on 3 June of Yellow Fever and was buried in the primary bastion of Fort Maltilde. When the French later regained possession of the islandVictor Hugues issued a declaration on 10 December " That the body of Thomas Dundas, interred in Guadeloupe, shall be taken up and given as prey to the birds of the air." This aroused great outrage in England and prompted a memorial in St.Paul's Cathedral.
