The 17-year-old midfielder became the most expensive player of his age when he secured a move to Germany, having broken into the Birmingham first team at the age of 16.
Bellingham, who is from nearby Stourbridge, made 41 appearances for his boyhood club and the Blues have retired his shirt number to inspire the next generation of youngsters.
"In such a remarkably short space of time Jude has become an iconic figure at Blues, showing what can be achieved through talent, hard work and dedication," a tribute piece on the club website read.
"His caring, humble and engaging off-the-field demeanour has also made him such an impressive role model. The 22 shirt has become synonymous with Jude, his rise to the first team aged just 16 years and 38 days, and these qualities.
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"And as such the club have decided it would be fitting to retire this number, to remember one of our own and to inspire others."
Bellingham himself professed his love for Birmingham but says that Dortmund is the right place for him to take the next step of his career.
"I do love the club and I struggle to hide how much this club means to me. I just hope the fans have enjoyed seeing me play," said the Blues' youngest ever player and goalscorer.
"It will always have a massive place in my heart because it's my club and the club I support, and it's been a privilege."
Birmingham narrowly avoided relegation by a margin of two points this term.