In a heartfelt message on social media, Diaz reflected on his three-and-a-half-year tenure at Anfield, saying: "I arrived with all my dreams, and I am leaving proud of what we achieved together.
"I have met incredible people, talented colleagues, and coaches who helped me grow. The fans are truly special, and I will always cherish the memories we made.
"We won trophies, but more importantly, we had a strong bond and friendship that made it all possible. We had our ups and downs, but we always stayed true to each other, just like a family should.
Diaz also paid tribute to his former teammate Diogo Jota, who tragically passed away in a car accident earlier this summer.
"I'm glad to be leaving with a sense of duty fulfilled and as a champion. It would have been a perfect goodbye if we hadn't lost Diogo in such a tragic way.
"I will always carry Diogo in my heart, and I know we'll never forget him. Thank you for everything. You'll Never Walk Alone."