Anders Holch Povlsen now owns 221,000 acres of Scotland with his portfolio outstripping that of the Duke of Buccleuch, who holds 217,000 acres.
Mr Povlsen, 46, made his fortune after inheriting fashion company Bestseller, which owns fashion brands including Vero Moda and Jack and Jones with the Dane also holding a 27 per cent stake in ASOS.
He made his first land purchase in Scotland in 2006 when he bought the 42,000-acre Glenfeshie estate in the Cairngorm National Park.
In just over a decade, he has spent around Â£70m on land acquisitions in Scotland, from Eriboll Estate in Sutherland to Tulloch Estate near Fort William, figures given to The Sunday Times confirmed.
At Glenfeshie, Mr Povlsen continues to forge his wild land vision after declaring the Victorian model of the Scottish sporting estate dead.
Although he still allows hunting and fishing at Glen Feshie, he is also a passionate environmentalist and has a 200-year-old vision to allow ecological restoration of the land.
Large numbers of deer have been culled with hopes that flora, fauna and woodland will have the right conditions to thrive.
Povlsen, who is intensely private and rarely gives interviews about his Scottish property, is believed to visit his estates once a month.
His personal wealth was recently valued by Forbes magazine at $5.8 billion
Richard Leonard, leader of the Scottish Labour Party, said: 'The sheer scale of this ownership shows that Scotland has unfinished business in land reform.
'It cannot be right that so much land, and therefore the wealth and the power that goes with it, can be concentrated in so few hands.
'We need land ownership for the man, not the few.'