The Dutchman has completed his £6million move to the Portuguese side.
Louis van Gaal is planning a Dutch revolution at Manchester United, but one Netherlands star will not be playing at Old Trafford any time soon.
The 22-year-old defender will make the £6million move from Feyenoord to the Portugues side, and will have a £31.7million buyout clause written into his contract.
Martins Indi was a key player in Van Gaal's Oranje side that secured third place at the 2014 World Cup. He looked to be an ideal replacement for defenders Rio Ferdinand and Nemanja Vidic, who both left Manchester United this summer.
Now Van Gaal must look elsewhere as he looks to fill the void at the centre of his defence. United have been linked to a big money move for Borussia Dortmund's World Cup winner, Mats Hummels.
Martins Indi said it was time for him to leave Feyenoord.
"It feels the right moment to leave," he said. "I have played more than 100 games for Feyenoord and now have a World Cup behind my name."
"I always said that if I made the next move in my career it must benefit both me and the club. My departure is a good financial deal for Feyenoord, while I get a new challenge in Portugal."