He was the younger son of Gavin Elliot of Midlem Mill, Roxburghshire, and his wife, Margaret Hay.

[1] Initially a writer, he began assisting in legal cases, helping William Veitch escape execution in 1679 as an opponent of King Charles II.

After similarly helping the Earl of Argyll in 1681, Elliot went into exile in Europe in 1685, and in his absence was sentenced to death and forfeiture.

He was pardoned by King James VII and returned to Scotland in 1687, where he was admitted to the Faculty of Advocates in 1688.

Elliot became a clerk to the Privy Council of Scotland, was knighted in 1692, and made a baronet, of Minto, in 1700.