Shoppers queued outside stores and car parks were full to capacity at malls across the country on the last full shopping day before Christmas eve.
Today is forecast to be the busiest day of the year in shopping malls and on the high street with customers spending an estimated £2.6m a minute.
The British Retail Consortium expects between £4bn and £5bn to be spent throughout this weekend.
At the Westfield Derby shopping centre, Richard Thornton, marketing and communications manager, said: "It is extremely busy, much busier than it usually is for this time on a weekend and the car parks were extremely busy when I was coming in this morning.
Peter Beagley, general manager at Glasgow's Braehead shopping centre, said shoppers were queuing outside stores before they opened at 9am.
He said: "By 10am our car parks were full and we had staff on duty directing cars to spaces when they became available.”
A spokesman at Sheffield's Meadowhall shopping centre predicted that 120,000 to 130,000 shoppers will pass through the doors today.
"Meadowhall, as expected, is busy," a spokesman said. "It's not mayhem but it is very busy."
Tom Nathan, Brent Cross shopping centre manager, said the next four days were likely to be "enormous for us in terms of sales".
He said that gloves and scarves were flying off the shelves. Headphones which double as earmuffs were selling at the rate of one pair every seven minutes.
But the Local Government Association said confidence on the high street remained low.
Its annual Christmas survey found that 84% of town centre managers said confidence among shoppers had either not improved or worsened compared with this time last year.
It also suggested that the particularly cold and wet start to the winter could also be taking its toll on the number of shoppers visiting town centres.
Normally the busiest day of the year is December 23 - the last day before Christmas Eve - but this year that falls on a Sunday when trading hours for bigger shops are restricted by law to just six hours.
M&S has responded by opening more than 100 of its stores at 12.01am on Christmas Eve morning to help shoppers get their Christmas essentials in time.
An M&S spokesman said: "We know that the days leading up to Christmas are some of the most hectic for our customers.
"Due to Sunday trading rules, we can only open for six hours on one of the busiest days of the year.
"We hope that these early bird hours on Monday will ease the pressure and give busy shoppers a bit more time to pick up Christmas food orders or last minute presents."
Waitrose, part of John Lewis, will also extend Christmas Eve trading hours in two thirds of its supermarkets by opening an hour earlier at 7am and closing an hour later at 6pm.
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