Some stores have cut prices by 80% in order to attract shoppers, and retailers believe it could be the busiest Boxing Day ever.
People arrived at Silverburn in Glasgow from 3am while more than 1000 people queued outside Next at Braehead shopping centre from 5am to get their hands on the best offers.
Silverburn's deputy manager George Reader said: "It's been nothing short of incredible, we've had people arriving at the centre since just before 3am this morning, which we've never seen before.
"Normally the Boxing Day sales are associated with clothes but people have been buying homeware, gadgets, phones, everything, people are still coming in and buying toys.
He added:"What we're finding is people who were given cash or gift vouchers as presents are all out today to make the most of the deals."
Gary Turnbull, general manager of operations at Braehead, added: ""Some people had even brought along folding camping chairs to sit on while they were queuing and had flasks of tea and coffee to keep them going.
"Shoppers were getting themselves keyed up for the dash to the first shop to open and bag themselves a bargain."
He said extra staff had been on duty to direct traffic around the car parks and by late morning, figures suggested it would prove to be a record-breaking Boxing Day.
Buchanan Galleries, in the centre of Glasgow, also reported brisk trade with thousands of people packing the stores. Centre manager Kathy Murdoch said: "The Boxing Day sales got off to a flying start this year, with shoppers queuing from the early hours to be the first into the Next sale which started at 6am.
"Retailers have all benefitted from this early rush with bargain hunters continuing to arrive in their droves throughout the day.
"We expect Friday to be as busy as John Lewis begins its clearance sale at 8am."
Ian McLelland, centre director at EK, East Kilbride said: "Despite many retailers starting their sales before Christmas, Boxing Day has proved yet again to be one of the busiest shopping days of the year in East Kilbride.
"We sold a significant number of EK gift cards over the festive season and judging from the crowds it looks like many of these have reappeared in Christmas stockings across the region.