A club statement said: "The arrangement will see the clubs work together on a number of aspects including the share of knowledge on and off the pitch, close co-operation between our first teams and Academies, training support and joint scouting, especially in Africa and further afield.
"We will also look to arrange friendly matches if our schedules allow, and we will continue to work together on many more opportunities from a footballing, branding and operational perspective. Galatasaray will spread the name of Reading FC in Turkey and we will do the same here in the Barclays Premier League."
Royals chief exec Nigel Howe said: "We are delighted to have signed this agreement and both clubs see this as a great opportunity. Working together with a club the size of Galatasaray can bring great positives to us at Reading.
"This is the first time we have entered into such an agreement and to do it with a club the size of Galatasaray is a real coup and we look forward to now bringing it to fruition."