Spending is predicted to soar by 31 per cent on last year as stores offer discounts exclusively on the internet following the Black Friday weekend.
Some of Britain’s biggest retailers will be hoping to avoid a repeat of problems which saw a number of their websites struggling to cope with the volume of traffic on Friday.
Around £943 million is expected to be spent online on Cyber Monday, up from £720m last year, according to Experian-IMRG.
The amount is expected to fall short of Black Friday’s predicted spending of £1.07bn – the first time that online retail sales in the UK were thought to have surpassed £1 bn in one day.
The Centre for Retail Research said spending online and in-stores over the four-days was expected to hit £3.49bn.
Retail giant Amazon reported record figures on Friday, with more than 7.4 million items ordered, leading to its biggest sales day ever in the UK.
Some companies struggled to keep their websites up and running on Black Friday.
The John Lewis website went down at around 3.20pm, with one IT analyst estimating the company could have lost £2.8m.