"Today, though my body still feels ready for challenges, my heart is not there anymore. I feel that right now it is time to give all of my attention to my family " he wrote on Instagram. "Therefore, I have decided to retire."
Szczesny won 84 international caps, the last at Euro 2024 where he started as Poland lost their first two group games but was rested for their last match, a dead rubber against France.
He played club football most notably for Arsenal and Juventus.
He recalled leaving Poland for Arsenal in 2006.
"Little did I know it would be a start of a journey of a lifetime," he wrote.
He joined Juventus in 2017 from Arsenal, where he won two FA Cups, succeeding the legendary Gianluigi Buffon.
He won three Serie A titles and three Italian Cups. In 252 matches for the club he kept 103 clean sheets.
On August 14, Juventus announced that they had agreed a mutual termination of their contract with Szczesny.
Italian media linked the goalkeeper with a possible move to a club in Saudi Arabia.
"I played the game at the highest level with the best players in history without ever feeling inferior," Szczesny wrote on Instagram.
"I gave the game 18 years of my life, every day, without excuses."
