The exclusion risks angering some UK shareholders whose approval is needed to complete the restructuring, which is aimed at making Unilever more agile, particularly when it comes to mergers and acquisitions.
The confirmation came in a notice posted on the exchange's website https://bit.ly/2O9xGcr and confirms previous guidance from Unilever that it was "very unlikely" to be eligible after becoming a single corporate entity incorporated and headquartered in the Netherlands.
The notice came hours after the maker of Dove soap and Lipton tea published a prospectus regarding its move that included a timeline for the December listing of its new Dutch entity.
FTSE Russell will select the company to replace Unilever PLC in the FTSE based on closing prices on Dec. 19, two days before the current UK and NV entities stop trading. Unilever has been one of the members of the FTSE 100 since its launch in 1984.
Unilever said in June that it planned to maintain a "premium listing" in London and hoped that investors who were impacted by its departure from the index would still be able to hold its shares.
Some funds do not invest in shares that are not part of the index of leading stocks.
"We continue to agree that restructuring Unilever makes sense, but are still of the view that Unilever's approach discriminates against UK shareholders," Columbia Threadneedle Investments, a top-10 Unilever shareholder, according to Thomson Reuters data, said in a statement.
Shareholders will vote on the move next month. Approval is needed from 75 percent of UK shareholders and 50 percent of Dutch shareholders.
Unilever shares were down less than 1 percent at 0932 GMT on Wednesday.
(Additional reporting by Nivedita Balu in Bengaluru and Simon Jessop in London; Editing by Mark Heinrich and Keith Weir)
By Martinne Geller and Simon Jessop