The Southwest London club have signed the Dutch goalkeeper on a four-year deal, delighting manager Martin Jol, who went after him in January.
"Maarten Stekelenburg is a fine quality goalkeeper who I know well from my time working with him at Ajax and of course as the Dutch international goalkeeper I have always had an additional interest in his career," said the Cottagers boss.
"I am sure that he will do well here at Fulham in the Premier League.
"He is a player of great quality and technical ability whose distribution and ability to react quickly and read the game is exceptional; he will be a fantastic addition to the talented team of keepers that we already have.
"I am delighted that he was so keen to come to join us and am very happy with the way that the summer is shaping up in terms of our signings, so on the whole I'm ever so pleased."