The goalkeeper made his final appearance for the club against Blackburn at the weekend after six years at St. Andrew's.
The 20-year-old has now formally linked-up with Premier League side Stoke City, the club he joined in January before immediately returning on loan to Blues to complete the 2012/13 campaign.
"Obviously I would have liked to have helped Blues get into the play-offs and fight for that chance in the Premier League, which was the target," said Butland. "Unfortunately we didn't quite achieve that but in development terms for me it was a brilliant season.
"Lee Clark gave me the opportunity to be his number one and I can't thank the gaffer enough for that and for keeping me in there. It was important that I got as many games as I could under my belt. In years to come I'll look back on this season as probably one of the most important of my career.”
Despite his exit from the club Butland feels there are positives on the horizon for Blues: “I can see good things happening and I hope they do," he said. "In the last couple or months or so we really picked up and showed the fans and other people what we’re about, which is a very good side. We finished on a high with good performances, a good spirit and playing the right type of football as well. We looked solid as a unit and were creating lots of chances as well, which bodes well for next season.
“The manager has come in this year and used a good mix of young and experienced players and it’s now paying off. Ahead of next season a lot of young players have been offered new contracts - the likes of Mitch Hancox, Callum Reilly and Koby Arthur. It’s good to see and the football that is being played can only be a positive for the club next year and I think it will be a successful one.”
Butland admitted that the perfect scenario would have seen him make his Premier League bow with Blues, rather than having to move on to pastures new, adding: “This club has taught me everything I know and it’s prepared me for the next step of my career. I would have loved to play with Birmingham in the Premier League, but sometimes you have to take into account personal goals in football, which is hard to do because Birmingham is such a big part of my career and such a big part of me now. I’ll never forget the time I spent here and the support that I’ve had from everyone in the club and the fans.
"I can only look back at what’s happened and the way I’ve been treated. From the time I joined when I was 14 up until now I’ve only got good memories of this place and that’s what I’ll take away. There’s not much more I can say other than a big thank you to everyone. I’ll always look out for Blues’ results. I can only wish the club; the fans and everybody involved all my best wishes and good luck for the future.”