The discount retailer, which trades as B&M Bargains, has more than 100 stores across the north of England, Wales and Scotland, and is one of a number of retailers to have taken advantage of empty Woolworths stores.
It has opened one store a week this year and finance director Steve Wakeman said the company would continue to do so during November.
"We have been delighted by trading at our new stores opened this year," he said. "Many were former Woolworths and occupy prime positions in their respective towns. The decision to open a further 40 stores in 2010 will also bring 1,200 much needed jobs to the retail sector."
In June the retailer reported a 93.7% rise in pre-tax profits to £14.2m on sales up 97.1% to £255.8m for the year to 31 December.