The 22-year-old joins the fellow Sky Bet Championship side on a three-year deal after Blues eventually accepted the Welsh club’s latest offer following a number of attempted bids.
Earlier this week, Adeyemi informed manager Lee Clark of his strong desire to further his career elsewhere and subsequently handed in a formal transfer request.
Following discussions with the player’s representatives, the club quickly sought a resolution to ensure that the manager's close-knit squad had no distractions ahead of the start of the 2014/15 season this weekend.
However, this was subject to Cardiff meeting the club’s valuation which eventually proved to be the case and personal terms were duly agreed.
The Board will now waste no time in backing the manager in his search for a suitable replacement for Adeyemi.
Adeyemi, who arrived from Norwich City last summer
, made 40 appearances, scoring on three occasions, during the 2013/14 campaign as he clinched the Young Player of the Season Award at PA14