Mamardashvili has signed for the Reds, though will spend this season on-loan with Valencia.
He posted to social media: "I can’t start talking about Valencia and this club without expressing my gratitude. Thank you for the continuous support and love I have felt at every stage since the first day of my arrival at the club for three years.
"Words are not enough to thank Valencia CF, this great football family and city has given me. Valencia didn’t just change my football career; it changed my life. I am forever grateful for the impact this club has had on me."We all know what a challenging year awaits us and how transformative this period is for the club.
"Therefore, I decided to stay in Valencia for one more year and give my best to help the club achieve its goal. As never before, we will fight to the end!"