After playing youth football with Sporting Club Accra, Abu signed for English side Manchester City on 31 August 2010. He was immediately loaned to Norwegian club Strømsgodset, where he made his professional debut. On 29 June 2011, Abu's loan deal was extended until December 2011. In October 2011, Abu signed a new contract with Manchester City, until June 2014. In January 2012, he joined German 2. Bundesliga side Eintracht Frankfurt on loan. Without playing a match he again was transferred to Strømsgodset at the end of March. On 19 May he scored twice in Strømsgodset's 3–2 victory over Fredrikstad. In August 2012, he joined Spanish club Rayo Vallecano on loan. He joined French club Lorient on loan on 1 February 2013. He signed a loan deal with Danish club AGF on 2 September 2013.
Strømsgodset
On 21 February 2014, Abu joined Norwegian side Strømsgodset again, this time on a permanent deal.
Columbus Crew SC
In January 2017 he signed for MLS side Columbus Crew SC. On 10 August 2018, Abu was sent on a season-long loan to Vålerenga. The deal was made permanent on 4 October 2018.
D.C. United
In March 2020, Abu was transferred to MLS club D.C. United on a one-year loan with a permanent option.
International career
Abu made his international debut for Ghana on 8 October 2011, as part of 2012 Africa Cup of Nations qualification. Against Sudan, he replaced Derek Boateng in the 75th minute of a 2–0 victory for the Black Stars. Three days later, in a friendly against Nigeria, Abu started for Ghana for the first time; he played 54 minutes in a scoreless draw. Although he had appeared just once in qualifying, Abu was included in Ghana's provisional squad for the 2012 Africa Cup of Nations on 15 December 2011. He was selected as part of the final 23-man squad on 11 January 2012, and would go on to appear twice at the tournament. Abu played once in the group stage, and then started in the third place match as Ghana were defeated by Mali. After appearing at AFCON, Abu would not be called back into the Black Stars setup for more than five years. In June 2017, he was called up by head coachJames Kwesi Appiah for a set of friendlies against Mexico and the United States, although he was excused from an earlier 2019 Africa Cup of Nations qualifier against Ethiopia.
