As part of the agreement, Berlusconi's TV production business Mediaset along with de Mol and investment bank Goldman Sachs has agreed to make a full bid for the remaining 25% of the production house "as soon as possible", according to an official statement from the company.
In February this year, Telefonica appointed investment bank Merrill Lynch and Italian finance firm Mediobanca to oversee the sale of its stake in the Dutch company.
At the time Telefonica said it had made the decision to sell its remaining stake in Endemol because the business was no longer central to its telecoms operations.
Telefonica had made it clear from as early as summer 2006 that it would be looking for an approach from a buyer.
The company previously turned down a £1.38bn offer for Endemol by Time Warner in October 2004.
Endemol's share price was up 0.85% to €24.86 this morning after the offer for the company was tabled and confirmed. This morning's offer for the company was valued at €25 per share including dividends.
The agreement is subject to regulatory approval.
Endemol was founded in 1994 by Mr de Mol and Joop van den Ende.
Last week, de Mol, through his company Cyrte Investments, bought The Hammer Horror Group, famous for producing 'The Curse of the Werewolf', 'Dracula' and 'The Brides of Dracula'.