With just a week left until the deadline, the winner, who is from East Dunbartonshire, is being urged by The National Lottery to claim their prize.
The player and two other individuals from Fife each scooped £1 million from EuroMillions Millionaire Raffle draws in the summer of last year.
The National Lottery is urging players to search for tickets and check the numbers.
For every EuroMillions line played, UK players automatically receive a EuroMillions Millionaire Raffle selection printed on their ticket.
Two of the winning tickets are from the special draw on July 26 when 100 lucky players were guaranteed winners of £1 million each.
The other winning ticket is from the July 23 draw.
The East Dunbartonshire winner has until 11pm next Wednesday to claim their prize. The winning ticket was CBT475280
A National Lottery spokesperson said: "There are three lucky winners in Scotland, including one in East Dunbartonshire, walking around not knowing they are millionaires.
"Though the clock is ticking, there is still time for players to re-check their tickets and, for a lucky trio, to make 2014 a year to remember as Scotland's newest millionaires."
If no-one comes forward with the winning tickets before the prize claim deadlines, then the prize money, plus all the interest it has generated, will go to the National Lottery Good Causes - adding to the £31 billion already raised through sales of lottery tickets since The National Lottery launched in November 1994.