They have also reached an agreement with Paris Saint-Germain striker Mauro Icardi on loan.
Icardi appears to be the jewel of their significant haul, still aged 29 with plenty of big-match experience, with Galatasaray able to position themselves as the beneficiaries of the Ligue 1 champions’ abundance of forward talent.
Mata, 34, is clearly closer to the end of his career, but with 41 international caps for Spain and over 50 Premier League goals, he will bring a valuable level of experience to a side currently sitting seventh on the Super Lig table through five games.
Adding to their influx of talent, Galatasaray also paid â‚¬6million to secure 19-year-old winger Yusuf Demir from Rapid Vienna, and â‚¬1.75m for 21-year-old centre-back Mathias Ross from the Danish Superliga.
Their late activity caps off a transfer period where they were also able to add former Napoli winger Dries Mertens on a free transfer, Arsenal midfielder Lucas Torreira for â‚¬6m and Benfica striker Haris Seferovic on a â‚¬1m loan.
ðŸ“¸ Transfer gÃ¶rÃ¼ÅŸmelerine baÅŸladÄ±ÄŸÄ±mÄ±z Juan Manuel Mata Garcia, Ä°stanbulâ€™da! pic.twitter.com/UTscDN3hBw
â€” Galatasaray SK (@GalatasaraySK) September 8, 2022