Porto have announced Casillas is retiring and will be joining the club's front office. The Spanish World Cup winner is recovering from a heart attack suffered at the end of last season.
"Iker Casillas will be part of the technical staff of the football team as soon as he recovers from his health problems," announced the club.
Casillas also said, "I'm going to make a connection between the team and the club, something different from what I usually do, which was to be on the field. I hope that together we can do a great job.
"We are going to prepare ourselves to have the best possible start for the campaign. We want to conquer the league, the cups and play a good role in Europe."