Podolski flopped at Bayern before reviving his career with FC Cologne.
He said: "I'm not one to look back and say 'if only', but maybe I was too young to do myself justice at a leading club like Bayern.
"Now it's a different story. I'm older, wiser and more mature. I have 100 caps for Germany and have seen so much more in this game. I can't wait to get started in the Premier League."