The move comes as part of a wide-ranging review at the Anglo-Dutch firm, which recently saw off a takeover bid from US food giant Kraft Heinz.
Analysts have said the sell-off could fetch $6bn (£4.8bn).
Unilever also intends to look at changing its historic status as a dual-listed company in two countries.
“We always have worked our operational model and driven efficiency,” Unilever’s chief executive, Paul Polman, told the BBC’s Today programme.
He said Unilever would not change its long-term business model, which he described as one of “sustainable value-creation”.
Alluding to the failed takeover bid, Mr Polman added that “the events of the last few weeks have pointed out that we have opportunities to drive further value in the business”.
Mr Polman said the firm would step up its cost-cutting, aiming for a 20% margin by 2020.
He said the margarine business was a “declining segment” that could be “better managed by others”.
Mr Polman said Unilever was studying whether to change its status and was looking at the wider “legal structure” of having bases in both the UK and the Netherlands. It will decide by the end of the year.
“Obviously it’s a very complex thing, the dual structure, and it requires the right focus to come to the right conclusions, but it will certainly simplify our organisational structure,” he told the BBC.