US owners Mondelez said the redundancies in Bournville, Birmingham, will be voluntary and will be phased in over the next two years.
A statement said: “From the outset, we have been clear that to secure the £75m investment and therefore the next generation of manufacturing at Bournville, we will need to become cost competitive.
“During consultation, we agreed that this would mean fewer people working in Bournville in the future than there are today.
“Our preference is always to look for voluntary redundancies to achieve any reductions. Through conversations with our workforce, a number of employees have asked for voluntary redundancy, indicating that we can achieve the necessary reductions through a voluntary approach.
“We have been clear as part of consultation that we need everyone to play their part if we are to secure the next generation of manufacturing at Bournville.”
Mondelez announced a proposed £75m investment at Bournville a year ago to build four state-of-the-art lines for making chocolate bars and chocolate assortments.
Bournville is the biggest Mondelez factory in the UK.