Son of Archibald Douglas, 4th Earl of Douglas and Margaret Stewart, eldest daughter of Robert III. He was Earl of Douglas and Wigtown, Lord of Galloway, Lord of Bothwell, Selkirk and Ettrick Forest, Eskdale, Lauderdale, and Annandale in Scotland, and de jure Duke of Touraine, Count of Longueville, and Seigneur of Dun-le-roi in France. In contemporary French sources, he was known as Victon, a phonetic translation of his Earldom of Wigtown.
He fought with the French at Baugé in 1421, and was made count of Longueville in Normandy. He succeeded to his father’s Scottish and French titles in 1424, though he never drew on his father’s French estates of the Duchy of Touraine. Douglas served as ambassador to England in 1424, during the ransoming of James I.
He also sat on the jury of 21 knights and peers which convicted Murdoch Stewart, Duke of Albany and two of his sons of treason in 1424, leading to the execution of Albany and the virtual annihilation of his family.
Following the murder of King James I of Scotland at Perth in 1437, Douglas was appointed Lieutenant General of Scotland, and held the office of Regent, during the minority of James II until to 1439. Douglas died from a fever in Restalrig, Midlothian, and was buried at Douglas.