The online seller, which relaunched in September, said its research found that 14 per cent of people plan to spend more today than they did on the equivalent day in 2015.
Of the 6.9 million shoppers planning to spend more, 1.9 million expect to do so by at least £100, and 241,000 by a minimum of £500.
David Anderson, managing director of BHS.com, said: “As an online retailer in the UK, Cyber Monday is an important time of the year for us. Last year, the nation spent £968 million in sales during Cyber Monday, a rise of 34 per cent on 2014 and our research suggests that this year could see further growth.”
The retailer said more than 60 per cent of its customer purchases are made on mobile devices, with its sales on Black Friday this year up 239 per cent from the previous Friday.