He has played twice for the club coached by his former team-mate Benni McCarthy since signing a one-year deal.
The 30-year-old returns to Africa after 12 years playing in Europe.
“I had other offers in Europe but this move was the right one for me, it feels great to return home playing again on African soil,” he told BBC Sport.
“But to play football to the fullest of your abilities, you have to be happy.
“So Cape Town City with its ambitions and objectives, as well as Cape Town as a city convinced me and my family to come over here.”
Nsofor joined City as a free agent after his contract at Darmstadt in Germany was terminated by mutual consent in January.
(Benni McCarthy) is a great guy and played a major role in luring me back to Africa and especially to Cape Town.
An 2008 Olympic silver medallist, Obinna has previously had stints at Chievo Verona, Inter Milan, Malaga, West Ham, Lokomotiv Moscow and MSV Duisburg.
After playing in Italy, Spain, Russia and Germany, Nsofor has set his sights on achieving success with the team coached by his former West Ham United team-mate McCarthy.
“ McCarthy and I played together during our time at West ham and we had a fantastic relationship together,” he explained.
“He’s a great guy and played a major role in luring me back to Africa and especially to Cape Town.
“My targets are the same as the clubs target which is to challenge for league and to win the finals of the MTN 8 trophy.”
Nsofor started his European career at Italian side Chievo Verona in 2005, playing three seasons at the northern Italian club, scoring 20 goals in 86 appearances, before joining Inter Milan in the summer of 2008.
He spent just one season at Inter before loan spells at Spanish side Malaga and English club West Ham.