John St Clair (died 1690) was a Scottish nobleman and the 17th Baron of Roslin.

He was the second son of William St Clair, 16th Baron of Roslin and his wife Dame Anna Spotswood, daughter of John Spottiswoode who was the Archbishop of Glasgow and later the Archbishop of St Andrews and Chancellor of Scotland.

His elder brother, William, had predeceased their father and so John succeeded to the estates of Roslin.

In November, 1666, John St Clair of Roslin raised letters of law against Herdmanston, inhibited him in 1667 and in 1668 received back the lands of Roslin from Robert Sinclair of Longformacus who had acquired Herdmanston's interest for 10,000 merks.

[1] During the Civil War, John St Clair, 17th Baron of Roslin defended Roslin Castle against Oliver Cromwell's commander General Monk who had with him 600 soldiers and artillery,[2] after the Battle of Dunbar.