Unilever has become the latest in a long line of companies to shut its UK final-salary pension scheme to the existing members.
The group, one of the biggest manufacturers of food and household products, said the scheme was "increasingly unaffordable and unsustainable".
The scheme has 7,000 active members and was closed to new joiners in 2008.
Unilever will start a 90-day consultation with staff and unions.
"Under the proposed new arrangements, existing final salary scheme members would be offered a two-part scheme consisting of a defined benefit career average plan plus a defined contribution investing plan with effect from 1 January 2012," the company said.
Separately, the Pension Protection Fund (PPF) said that in March the 6,533 final-salary schemes in the private sector had a combined surplus of £45.5bn.
That was slightly lower than the surplus of £48.4bn at the end of February.