Uchechi, who has represented his country at Under-20 and Under-23 level, is set to sign the contract before the January transfer window closes at 11pm today.
The 22-year-old started his career at Charlton Athletic, but turned down a move to Wigan to sign for West Ham in 2009. After leaving London he moved back to Nigerian football with FC Dender before a loan spell with Leicester City last term.
Uchechi becomes the fifth arrival at Pittodrie during a busy transfer window, with Dons boss Craig Brown also adding Mark Reynolds, Russell Andeson, Stephen Hughes and Gavin Rae to his squad this month.
The Dons have also secured Scott Vernon, Andy Considine and Isaac Osbourne on extended contracts, and only Richard Foster and Jack Grimmer have left the club so far.