The investment is to keep prices of daily essentials and Christmas-themed products low by March next year.
Sainsbury’s has set aside more than £15m on both seasonal and traditional treats, which would reduce the cost of a Christmas roast to £4 a head.
The announcement comes after the retailer spent £65m across its business to help customers address the crisis over the past few months.
The latest investment would take Sainsbury’s total spending on cost reduction to £550m in the two years to next March.
Sainsbury’s chief executive Simon Roberts said: “We really understand that millions of households are having to make really tough decisions this Christmas and our job is to do everything we can to help with the rising cost-of-living.
“We are accelerating our commitment to being the best value, investing a further £50m in lowering prices and doing everything we can to fight inflation and help our customers enjoy celebrating this year.
“We know everyone wants to enjoy a special Christmas meal together, which is why we’re keeping inflation at bay and offering Christmas roast dinner for less than £4 per head – cheaper than it was last year.
“I would like to thank every one of my colleagues who are working tirelessly to deliver a brilliant Christmas for our customers.
“Our entire team at Sainsbury’s are working together to offer the best value, innovative new products and leading customer service.
“We’re all looking forward to welcoming our customers into stores and online at this special time of year.”
In September this year, Sainsbury’s invested £25m as part of a cost-of-living support package for its hourly paid colleagues.
The company currently employs 171,000 colleagues across its operations.