Asamoah was scouted playing for a local based club, which belongs to Kamara and was recommended by the scout Mr. Charles Mensah Gapson to the late Alhaji Sly Tetteh, former CEO of Liberty Professionals. He joined Swiss club Bellinzona and was loaned to Italian side Torino in the winter of 2007–08.
In June 2008 Asamoah was signed by Serie A club Udinese where he established him self and became a linch pin. He eventually established himself for both club and country. After some good performances at the 2010 World Cup and Africa Cup of Nations, he became a target of top clubs in Europe.
Asamoah and Udinese teammate Mauricio Isla both joined Juventus in July 2012 on co-ownership agreements, with Juventus paying €9 million for 50% of Asamoah's contract. He made his debut on 11 August against Napoli in the Supercoppa Italiana and scored; Juventus went on to win 4–2 after extra time.Due to his impressive performance against Napoli Antonio Conte who the coach of Juve during that period decided to start him. He started in the Serie A opening match against Parma and made an immediate impact by setting up Stephan Lichtsteiner's goal in a 2–0 win.