The 22-year-old winger, who had been on-loan from Arsenal, has put-pen-to-paper on a three year contract at St Andrew's and is now setting his sights on putting in performances good enough to warrant England international recognition.
"My agents and myself held long talks and I think it's the right decision that I've made," Pennant told Sky Sports News.
"If I carry on playing well then my aim is to play for England.
"If I fulfill my potential and play well week-in-week-out in the Premier League then playing for the national team is where you are going to end up playing.
"I'll be doing my best for Birmingham City and we''ll see what progresses from there."
Blues will pay Arsenal up to £3million for Pennant's services and as well as signing him to a three year deal they also have a one year option on the player.