Bertrand Traore has been granted a work permit and will be available to play for Chelsea from the 2015-16 season.
The Burkina Faso midfielder agreed a deal with the Stamford Bridge club in October 2013, but had not played enough international football to be given a permit.
Traore was sent on loan to Eredivisie side Vitesse, where he made 48 league appearances across one and a half campaigns
The 19-year-old was particularly impressive in 2014-15, netting 14 goals in 33 outings as Vitesse secured UEFA Europa League qualification.