The goalkeeper starred for Levante in La Liga last season before then enjoying a superb World Cup campaign, helping Costa Rica to reach the quarter-finals for the first time in the country's history.
Navas' form did not go unnoticed and European champions Real Madrid finalised a deal to bring him to Santiago Bernabeu on a six-year deal on Sunday after weeks of speculation.
The 27-year-old, who joins Iker Casillas and Diego Lopez as the Blancos' shot-stopping options, was formally presented to the press at the Santiago Bernabeu on Tuesday and was ecstatic to be joining the European champions.
"Today is the biggest day of my career," Navas told reporters in the Spanish capital. "This is what I really wanted and now I am part of the best club in the world.
"I will give everything for this shirt in every practice and in every game that I play; I hope to help Real Madrid get many titles.
"I want to thank Real Madrid for trusting me and I thank God for making my dream come true."
Madrid president Florentino Perez insisted the club have every confidence in the Costa Rican, who is expected to compete with captain Iker Casillas for the No.1 jersey this term.
"We have an excellent team, but we must also strengthen it," the Blancos supremo said. "We have special and unique challenges, such as the Uefa Super Cup and the Club World Cup.
"Thus, today we present one of the best goalkeepers in the world. Navas has demonstrated in recent years his huge professionalism, his sacrifice and his quality. He had offers from some of the top clubs, but wanted to play here.
"Welcome home, Keylor. It will be the first time a player from Costa Rica play here, you'll have the honour and pride to do so. All Costa Rica will be at your side, and all Real Madrid fans around the world."
Navas' arrival is set to result in the departure of Lopez, even thought the former Sevilla man was Carlo Ancelotti's first-choice shot-stopper for the majority of the 2013-14 Liga campaign.