Osei began his career in 2001 with Ghanaian regional club Echomog, and moved to Suhum Maxbees of the Poly Tank Division One League a year later. He transaferred to Accra Hearts of Oak SC, before moving to Turkey to play for Ak?aabat Sebatspor (then in the TFF Super League) in 2003. In 2004, Osei joined Livorno, going much unnoticed for the majority of the season. In two appearances in May, Osei played in consecutive defeats where the team conceded 12 goals in two games against Parma and Siena.

The following season, Osei was loaned to FCU Politehnica Timişoara, with the Romanian club having an option to buy him at the end of the season. He was eventuaslly released by Livorno, and returned to play in the Ghana Premier League, playing for ASV Cham, Wa All Stars and Liberty Professionals[1]. Osei signed a Major League Soccer contract with the New England Revolution on March 31, 2009.

International

Osei was part of the Ghanaian 2004 Olympic football team, which exited in the first round, having finished third in group B. He also has one cap for the senior national team.