Dons boss Derek McInnes made the move for the Brighton winger after missing out on Zeli Ismail, who instead joined Notts County.
The 20-year-old has yet to feature for Brighton, but played four games for Crawley while on loan last season.
The forward, who joined the Seagulls from Preston in January 2014, becomes the fifth summer arrival at Pittodrie.
McInnes told RedWeb: "Jeffrey is a player we have been aware of for some time.
"He will offer additional competition in the wide areas, where he brings real pace."
Source: BBC Sport