It also plans to extend its Simply Food network, with 70 new stores expected to open this year.
Branded products will be trialled in 20 large stores in the North East from the end of July.
M&S chief executive Stuart Rose said that if they prove a hit, about 350 products would be rolled out across the country, a move which could come as an unwelcome shock for c-store operators near M&S stores.
Rose explained that customers regularly complained that they couldn't buy their favourite branded products in M&S stores and were having to make two shopping trips.
The announcement was made as M&S revealed its full-year results. Pre-tax profits for the 52 weeks to March 29 surged by 20.5% to £1.13bn on sales up 5% to £9bn.