Sasic, who won the Champions League with Frankfurt last season, was the leading goalscorer at this summer’s Women’s World Cup in Canada.
The 111-cap striker, who has 63 international goals to her name, says she is now looking forward to new challenges in life.
“I have decided to go a new way and end my playing career,” Sasic said.
“I am looking forward to many new things in my life: my university studies, a new orientation job-wise and starting a family among many other things.”
Germany manager Silvia Neid admits she is disappointed by Sasic’s decision but says she wishes the striker all the best for the future.
“I regret Celia’s decision, but she also understands that football is not everything in life and there always comes a moment in life when you need to focus on other priorities,” Neid said.
“She was always a role model, on and off the pitch. We won important games because of her; she took on responsibility and completely fulfilled her role as a leading figure.
“From the bottom of my heart, I wish her all the best for the next step in her life.”