He began his career as a trainee with
Bristol City, turning professional in June 2000. He was given a new two-year contract while injured, but struggled to re-establish himself at
Ashton Gate after returning from injury, having loan spells at
Torquay United in January 2003, and
Cheltenham Town in August 2003. He eventually left Ashton Gate in February 2005, when he signed for
Yeovil Town, initially on loan, and then on a permanent basis. Amankwaah signed for
Swansea City in July 2006 for a fee of £250,000. Amankwaah joined
Swindon Town in June 2008. He played 89 games for the club, scoring 5 goals before being released on 31 August 2011. Amankwaah still had 6 months to run on his contract when he was released. On 2 July 2012, Amankwaah signed for League Two side
Exeter City on a free transfer. On 30 April 2013, he was released by Exeter along with 3 other players after the expiry of his contract. After a successful trial with
Northampton Town, Amankwaah signed a one-year contract with the option of a further year on 29 July 2013. He made 24 appearances for the Cobblers before having his contract terminated on 23 January 2014. On 17 February 2014, Amankwaah signed for
Conference Premier side
Salisbury City, making 14 appearances for the Whites. Amankwaah signed for
Sutton United in September 2014. He made a total of 21 full and two substitute league appearances in the 2014–15 season, scoring his first goal for the club when he volleyed in a corner in the last seconds of the game against
Chelmsford City on 4 April 2015 to claim a 1–0 victory for Sutton. Amankwaah made 28 full and three substitute league appearances in the 2015–16 season, helping the U's to lift the
National League South title. He netted his second league goal from another corner against
Margate on 9 April 2016, a game which Sutton went on to win 4–0. Amankwaah scored his first goal in Sutton's 2016–17
National League campaign when he scored a consolation goal in a 3–1 away defeat to
Dover Athletic on 4 October 2016. On 19 October 2016, it was announced that Amankwaah had signed a one-year contract extension with Sutton United and will stay with the club until the end of the 2017–18 season. Amankwaah made his 100th career appearance for Sutton on 3 December 2016 in a 2–1 win against
League Two club
Cheltenham Town in the
FA Cup 2nd round. He went on to appear in every round of Sutton's historic run to the 5th round of the FA Cup for the first time ever, including appearances in a 3–1 victory over local rivals
AFC Wimbledon of
League One on 17 January 2017, a 1–0 victory over
Championship side
Leeds United on 29 January and an eventual 0–2 defeat to
Premier League club
Arsenal on 20 February. ==International career==