The 21-year-old was a free agent after leaving Norwich City and Blues boss Lee Clark has moved quickly to make him his sixth capture of the summer so far.
Adeyemi’s services were in-demand after he impressed during a loan spell with Brentford in League One last season and he will officially become a Blues player on 1 July.
“He’s a player I know really well,” said Clark. “I worked with him during my time at Norwich when he was a youngster at the club.
“I’ve followed his progress since, He’s done exceptionally well on loan at a few different clubs and I’m delighted to bring him here.
“Tom is a terrific young lad who is a powerful and athletic midfield player who can get forward and score goals.”
Adeyemi made 39 appearances for the Bees, scoring three goals, as Uwe Rosler’s side narrowly missed out on promotion to Yeovil Town in last season’s play-off final.
Born in Norwich, he worked his way through the youth system at his hometown club and turned down an offer from Cambridge University in favour of a professional contract at Carrow Road.
He made his first-team debut at the start of 2009/10 and was also named League One Apprentice of the Year that season.
A loan spell at Bradford City followed and Adeyemi made an instant impact, finishing the 2010/11 campaign with five goals from 37 appearances.
He continued to flourish, this time in League One with Oldham Athletic, where he chalked up another three goals from 45 outings before linking-up with Brentford last August.
You can read Tom Adeyemi’s initial thoughts on joining Blues, plus an exclusive BluesTV interview, here on bcfc.com shortly.