Polman formally takes over as chief executive from Patrick Cescau at the end of the year and will be the first external chief executive in Unilever's history.
He joins Unilever from Nestle, where he is currently executive vice-president and zone director for the Americas region.
According to a report in the Financial Times, investors in Unilever, famous for its Persil, Dove and Flora brands, expect Polman to drive the group harder and produce stronger sales and profits growth,
One told the FT that he was looking to Polman to "raise the metabolic rate" of Unilever, while another said he was optimistic about Polman's prospects. "It is not that the other executives are no use. They have a high level of ability but the corporate culture under Cescau was pretty bad and it was just creaking forward."
Shareholders have ruled out a fundamental overhaul of the business.
One former executive described his appointment as a "radical" move: "It's a real tribute to the strength of the Unilever brand that it has taken such a radical view of itself and knows it's got to change."
Polman joined Nestle in 2006 as chief financial officer and prior to that enjoyed a 26-year career at Procter & Gamble, where he rose to become group president for Europe from 2001 to 2005.