As part of the investment, the retailer has introduced an additional Autumn pay review for the first time and other benefits for staff.
From 1 October, the hourly pay of more than 40,000 colleagues will increase to a minimum of £10.20, which is above both the national and real living wage.
This comes after the retailer increased its staff pay from £9.50 to £10.00 in April this year, representing a 7.4% annual rise since the start of the year.
In addition, M&S will provide a one-off £250 voucher to spend at its stores for its 4,500 salaried colleagues at pre-management levels in its stores and support centres.
The free food policy was initially limited to store staff, but is being expanded to workers at M&S’ distribution centre in Castle Donington.
From this month, the retailer is also offering free sanitary products to workers across stores and sites.
M&S chief executive Stuart Machin said: “Whether you’re running a home or running a business, everyone across the country is feeling the pressure of rising costs.
“We want to do what we can to help ease some of that strain; that’s why we have invested in price to deliver better value for our customers and, why we are investing in our colleague base pay for the second time this year.
“Our colleagues are our biggest asset, and we want to ensure they are fully supported and rewarded for the remarkable contribution they make to M&S.”