The former Nigeria youth international has not yet made a senior appearance for the Citizens after joining from Shuttle Sports Academy in 2014.
Nwakali reportedly met up with Aberdeen on Wednesday morning at their winter warm training camp in Dubai and is expected to feature in their friendly against Lokomotiv Tashkent on Sunday subject to clearance of a work permit.
"He is a player we have been looking at for quite a while and we are delighted to have him on board," Dons boss Derek McInnes told the Aberdeen Evening Express. "I am sure he will prove to be a valuable addition."
The 21-year-old was an Under-17 World Cup winner having achieved glory with the Super Eagles in 2013, and will be looking to make an impact in Scotland after previous loan spells in Spain and Norway.