[4] After half a year in Indonesia for Persijatim, he joined Singapore Armed Forces in January 2005 and signed back to PSIS Semarang in early 2006.
[5] He played for PSMS Medan one year before being signed in January 2007 for Persis Solo,[6] after 14 goals in 28 games in the 2007–08 season was sold to Persija Jakarta.
After many speculations, in August 2011 Football Association of Indonesia finally confirmed that Nwokolo has been naturalised, and got Indonesian citizenship officially on 10 October 2011.
[10] Nwokolo made his debut for the Indonesia national football team in the 2015 AFC Asian Cup qualification campaign against Saudi Arabia on 23 March 2013.
[11] On 15 April 2014, after the Persipura Jayapura vs Persebaya Bhayangkara match conference, Greg got into a fight with Jacksen F. Tiago because of personal problems that started in the Indonesia national football team.