Major shareholder Royal London Asset Management, which owns more than 0.7 per cent of Unilever shares on the London Stock Exchange, is planing to vote against the move.
It comes after leading shareholder advice group Pirc urged all investors to go against the proposal.
M&G Investments, Columbia Threadneedle, Legal & General Investment Management and Lindsell Train have also publicly voiced opposition to the move.
Mike Fox, head of sustainable investments at Royal London, said: “We think that Unilever is a high quality company… and have decided to vote against the upcoming resolution.
“Should the motion succeed, we would be forced to sell our holdings in Unilever plc across a number of our funds, something we do not believe would be in the interests of our clients.’
Pirc said: “The affected holders are likely to be some of the longest-held shares – and the board has been short-sighted to presume that they have no voice.”
Two of the biggest trade unions in the UK have also since come out to support ditching the proposed Dutch relocation.
Unite and GMB were on the side of shareholders as they called on Unilever to not “flee overseas” from Brexit.
Unite national officer Rhys McCarthy said: “Investors understand the need for great British-based companies like Unilever to retain their headquarters in the UK.”
He added: “The UK’s weak takeover rules which put short-termism ahead of the long term are clearly a major factor in Unilever’s proposed move following a failed hostile takeover bid, as is the swirling uncertainty around Brexit.
“Ministers need to get a grip on Brexit and toughen takeover rules to stop more firms like Unilever seeking to flee overseas.”
Eamon O’Hearn, GMB national officer, said he “welcomes UK investors’ increasing opposition to the Unilever proposals”.
Analysts at investment bank Jefferies warned such a move could spark a £1.2billion fire sale of Unilever shares in the run-up to Christmas.
Unilever has said in previous statements: “The proposal to simplify Unilever’s structure will bring clear strategic benefits for shareholders, including even stronger governance and the move to a ‘one share one vote’ principle.”