Frimpong was born in
Mampong. He began his career in Nigeria with
Gabros of Nnewi and
El-Kanemi, where he became top scorer and earned a move to
Enyimba F.C. He won the
CAF African Champions League with Enyimba in 2003 and 2004, scoring a total of 14 goals, but he missed the 2005 competition through injury. He signed on loan for Saudi Arabian side
Al-Nasr on 3 February 2006, with an option to make the deal permanent. He left the club on 7 April 2006, scoring three goals in ten appearances. Frimpong signed for
CS Sfaxien of Tunisia later in 2006, and made an immediate impact in the group stages of the CAF Champions League. He scored a vital goal in the first-leg of the final and on 16 February 2007 his wish was granted, after he signed a three-year deal with Swiss Premier side
BSC Young Boys. He made his league debut for the club on 25 February 2007, in a 3–1 victory over
FC Thun; Frimpong celebrated his debut with two goals. In September 2007, Frimpong was handed a four-match ban and given a fine of 1,100 US dollars after assaulting
St. Gallen player
Jürgen Gjasula during a league match. The Swiss FA decided not to give him the maximum six match ban after video evidence showed that he was provoked by Gjasula. On 6 September 2008, he was loaned to
FC Luzern. ==International career==