Walter Stewart, 1st Lord Blantyre (died 1617) was a Scottish politician and judge.
The son of Sir John Stewart of Minto and Margaret Stewart of Cardonald
Educated with James VI under George Buchanan, he was Knight of Cardonald, Prior of Blantyre, Keeper of the Privy Seal of Scotland from 1582 to 1596, an Extraordinary Lord of Session from 1593, an Octavian from 1596, Lord High Treasurer of Scotland from 1596 to 1599.
He was imprisoned and compelled to resign by James VI in 1599. He was a commissioner for union with England in 1604. He was created Lord Blantyre, in the Peerage of Scotland in 1606, and succeeded by William Stewart.