The Wrexham shot-stopper recently received his first senior call-up for Nigeria after completing his international switch, ending his long association with England's youth national teams.
Okonkwo revealed that discussions with the Nigerian Football Federation began last year, with the goalkeeper admitting the opportunity to represent the country of his heritage was too important to ignore.
"It is a privilege to be granted the chance to play for your country. I am extremely excited and eagerly await the opportunity. I have been looking forward to this moment for quite some time, and to finally have the chance is remarkable," Okonkwo told the Super Eagles media team, as quoted by African Football.
"The process began last summer when I spoke with the manager and the goalkeeping coach. They expressed their interest in me, and the discussions were very encouraging. Since then, we have been working to finalise my switch from England to Nigeria."
The 24-year-old also shared the emotional reaction from his family after learning he had been selected for the upcoming Unity Cup tournament in London.
"When the moment finally came, the goalkeeping coach was the first to message me, letting me know that I had been selected for the camp. You experience a surge of excitement. The first two people I called were my dad and my mum," he added.
Okonkwo says his decision ultimately came down to his ambition of helping Nigeria compete for trophies on the international stage.
"The reason for my decision is that I aspire to win trophies for my country. I understand how much Nigerians cherish football and how significant it is to them, and being able to contribute to that for my country and my roots would be extraordinary."
He is expected to make his senior debut when Nigeria face Zimbabwe in the Unity Cup semi-final on 26 May.