Florentino: Mourinho will bring good times back to Real Madrid
Perez confirmed at a press conference at the Bernabeu on Wednesday evening that the club had parted company with coach Manuel Pellegrini and that Mourinho was their chosen replacement for the Chilean.
"The change of coach is always difficult, but we are convinced that after this first year and this first phase, now is the moment to give a fresh impulse to our project," he said.
"I am absolutely convinced that the incorporation of Mourinho, who is one of the best coaches in the world - if not the best - is an opportunity that, in this Madrid, which fights permanently for excellence, we couldn't let pass us by."
Madrid have now won just two major trophies in the last seven years, whilst being knocked out of the Champions League at the last-16 stage in each of the last six editions.
"A year ago there was a huge and unprecedented effort to configure and put together a squad capable of aspiring to the maximum," said Perez.
"We have advanced a lot, but we still have a lot of ground to cover.
"This club demands the maximum and is always in search of excellence.
"We have reflected a lot on this season. It's not just not winning a title. We consider that we are in a suitable moment to bet on one of the best coaches in the world, and the opportunity to bring him to the club is there."