"Thank you, football. And to all who accompanied me and made me a better player and person along the way," he wrote on X.
Liverpool released Thiago when his contract expired at the end of last season.
"Technically, he is so, so good," said then-manager Jurgen Klopp when the decision was announced. "A talent who could play in any team in the world and it was a privilege to have him with us."
"Injuries have been a frustration for him and also for us but the level that he was able to play at when he was available was incredible."
He was born in Italy, where his father, Mazinho, a member of Brazil's 1994 World Cup winning squad, was playing for Lecce. Thiago's brother Rafinha, a Barcelona-born Brazil international, plays in Saudi Arabia.
Thiago started his senior career with Barcelona in 2009, where, among other trophies, he won four LaLiga titles, the 2011 Champions League and Club World Cup. He then spent seven years at Bayern Munich winning the Bundesliga every season.
His haul in Munich also included the Club World Cup in 2013 and the Champions League in 2020. In four years with Liverpool, he won the FA Cup and reached a third Champions League final
Thiago won European under-17 and under-20 titles with Spain and won 46 senior caps for Spain between 2011 and 2021 but missed the Euro 2012 triumph with a back injury.
"I will always be willing to give back what I have been given and I am grateful for the time I have enjoyed it," said his X post.
