Born in Accra, Osei began his career in 2001 with regional club Echomog, and moved to Suhum Maxbees of the Poly Tank Division One League a year later.
The following year Osei was loaned to FC Politehnica Timișoara, with the Romanian club having an option to buy him at the end of the season.
He was eventually released by Livorno and, after a brief spell in Germany with amateurs ASV Cham, returned to his country to play in the top level, representing in quick succession Wa All Stars and Liberty Professionals.
[1] On 31 March 2009 Osei signed with Major League Soccer's New England Revolution,[2] being waived in January 2011.
[4] Osei was part of the Ghanaian 2004 Olympic football team which exited in the first round, having finished third in group B.