Irish Under-19 international O'Keeffe, a First Year Professional, has caught the eye of manager Gary Rowett in the Development Squad.
Birmingham-born O'Keeffe, an athletic, versatile player, was singled out by Rowett recently as one likely to follow the likes of Reece Brown, Viv Solomon-Otabor, Jack Storer and Josh Dacres-Cogley into his senior plans from within the ranks.
O'Keeffe, 18, can play right-back, right midfield or central midfield.
His drive, determination and leadership qualities allied to ability has seen the former Baverstock School pupil emerge as the next prospect with potential to make the breakthrough from the Academy.
Blues, meanwhile, are to take an extended look at winger Ollie McCoy.
The Beaconsfield player has appeared for the Under-23s this season, scoring in the Birmingham Senior Cup tie at Highgate United.
Paperwork has been completed that allows him to be registered as a trialist until the season's end.
Blues have also taken McCoy's team mate, striker Callum Bunting, on a similar arrangement.