The 17-year-old has signed a two-year deal having being promoted to the first-team squad in recent weeks.
The young forward was playing non-league football little over a year ago but was spotted by Birmingham's youth scouts and snapped up.
His performances for Birmingham's youth sides had seen a number of Premier League clubs linked with a possible move, but he has committed his future to the Blues.
"I have been hugely impressed with Koby and he has now become involved with the first team group on a daily basis," manager Lee Clark told the Birmingham Mail.
"He has a big future ahead of him and he fits the bills in terms of my philosophy of building a young, hungry and talented squad here at Birmingham City."
Blues Academy manager, Kristjaan Speakman, added: "It's testament to the recruitment department, through a network of contacts and scouts we have managed to identify and recruit the player in a competitive arena.
"Furthermore, the staff have been fantastic in making Koby feel welcome, going out their way, easing the transition to life at the Academy.
"I'm sure that this combined with the manager's philosophy is why he has chosen to commit himself to Birmingham City FC."