George Baillie was born on 16 March 1664. He was the son of Robert Baillie of Jerviswood and, through his mother Rachel, grandson of Sir Archibald Johnston of Warriston, Edinburgh, Lord Warriston in the Cromwellian Parliament.
Baillie’s father was executed in 1684 on a charge of complicity in the Rye House plot, and after the execution the younger Baillie fled to Holland with his father’s political associate, Sir Patrick Hume, who later became the 1st Earl of Marchmont. When William of Orange ascended the throne, Baillie returned to Scotland and played a prominent role as a leader of the Squadrone, whose votes gave the Act of Union a majority in the Scottish Parliament. Earlier, in September 1691 he married Grisell, the daughter of Sir Patrick Hume.
He served in the Scottish Parliament as MP for Berwickshire, 1693-1698, and 1700-1701, and MP for Lanarkshire 1703-1707. Then in the British Parliament he served as a Lord Commissioner of Trade, 1710-1712, as a Lord Commissioner of the Admiralty, 1714-1717, and as a Lord Commissioner of the Treasury, 1717-1725.
Between May 1731 and October 1733, Baillie spent time in Italy with his wife. In 1734 he stood down from his Parliamentary career, and on 6 August 1738 he died.